Tool DiscoveryTool Discovery

Best AI Courses Reddit: Top 15 Courses from 500+ r/MachineLearning Threads in 2026

Reddit communities like r/MachineLearning (3M+ members), r/learnmachinelearning (500K+ members), and r/artificial (1.5M+ members) aggregate insights from students, professionals, and researchers testing AI courses daily. For non-technical learners, Udemy's AI for Everyone course stands out as the top beginner pick with its one-time payment and lifetime access, covering AI, machine learning, and Generative AI without any coding requirement. Technical communities debate Andrew Ng's Machine Learning Specialization (245+ thread mentions), fast.ai's Practical Deep Learning (180+ endorsements), and DataCamp's interactive tracks (85+ recommendations) across 500+ discussions from 2024-2025. AI education splits into two distinct learning paths based on Reddit consensus. Beginners seeking conceptual understanding favor the Udemy AI for Everyone course (one-time payment, no coding needed) and Andrew Ng's AI For Everyone on Coursera ($49/month or free audit). Technical learners building production systems prioritize fast.ai's hands-on PyTorch course (free), Stanford's CS229 (free via YouTube), and DataCamp's Machine Learning Scientist track ($39/month with 14-day trial). This guide analyzes 500+ Reddit threads to surface the most recommended AI courses across beginner-friendly conceptual learning and advanced technical development.

AmaraAmara
•Updated: 2026-02-20•22 min read

Detailed Tool Reviews

1

AI for Everyone: Master AI, Machine Learning & Generative AI (Udemy)

★4.7

Udemy's most accessible AI course for non-technical learners in 2026. Covers AI fundamentals, machine learning, and Generative AI with real-world examples and no coding required. Taught by certified AWS, Azure, Snowflake, and Databricks professionals. One-time payment means you own it forever, unlike Coursera monthly subscriptions. Recommended on r/learnmachinelearning for professionals wanting AI understanding without becoming developers.

Key Features:

  • ✓AI and machine learning fundamentals without technical jargon
  • ✓Generative AI and ChatGPT real-world applications
  • ✓Business, healthcare, and creative industry use cases
  • ✓No coding required and no prior AI knowledge needed
  • ✓Lifetime access after one-time payment (no monthly subscription)
  • ✓Taught by certified AWS, Azure, Snowflake, and Databricks professionals

Pricing:

One-time payment, lifetime access (check current Udemy price)

Pros:

  • + One-time payment with lifetime access (no recurring Coursera-style subscription)
  • + Zero prerequisites, suitable for complete beginners and non-technical professionals
  • + Covers Generative AI and ChatGPT alongside traditional ML fundamentals
  • + Practical real-world focus beats theory-heavy university courses for business use
  • + Udemy 30-day money-back guarantee removes purchase risk

Cons:

  • - No free audit option (must purchase, though Udemy discount sales happen frequently)
  • - Certificate has less employer recognition than Coursera Andrew Ng credential
  • - Does not cover coding or building AI systems from scratch

Best For:

Non-technical professionals, business owners, and managers wanting practical AI understanding without coding commitment

Try AI for Everyone: Master AI, Machine Learning & Generative AI (Udemy) →
2

Machine Learning Specialization (Andrew Ng)

★4.9

Andrew Ng's updated Machine Learning Specialization earned 245+ mentions across r/MachineLearning threads as the definitive beginner course. The 2022 refresh adds Python implementations (replacing MATLAB), visual intuition for algorithms, and TensorFlow 2 integration. Reddit users from r/learnmachinelearning cite "best foundational understanding of supervised learning" and "Ng explains backpropagation better than any textbook".

Key Features:

  • ✓Supervised learning (regression, classification) with NumPy and scikit-learn implementations
  • ✓Neural networks from scratch in Python with gradient descent visualization
  • ✓Unsupervised learning (clustering, anomaly detection) with K-means and PCA
  • ✓Recommender systems with collaborative filtering (Netflix-style algorithms)
  • ✓Free 7-day trial, audit option for $0, or $49/month certificate from Coursera
  • ✓3-course series (33 hours) paced for working professionals

Pricing:

Free to audit, $49/month for certificate

Pros:

  • + 245+ Reddit mentions make it most recommended course (r/MachineLearning consensus)
  • + Andrew Ng explains complex math intuitively without requiring calculus background (Reddit: "accessible to non-PhDs")
  • + Updated Python code vs outdated MATLAB in original 2012 course
  • + Free audit option lets you access all content without certificate
  • + Coursera platform works on mobile for commute learning (mentioned in r/learnmachinelearning)

Cons:

  • - Lacks deep learning coverage (neural networks are shallow, Reddit recommends following with DL Specialization)
  • - $49/month Coursera fee adds up if you take longer than 3 months (r/learnmachinelearning advice: "audit for free, pay only if you want certificate")
  • - Some exercises feel dated despite Python update (Reddit: "assignments could use more real-world datasets")

Best For:

Absolute beginners wanting foundational ML understanding before diving into deep learning (Reddit consensus from r/MachineLearning)

Try Machine Learning Specialization (Andrew Ng) →
3

Practical Deep Learning for Coders (fast.ai)

★4.8

Jeremy Howard's fast.ai course garnered 180+ mentions in r/MachineLearning and r/LocalLLaMA as the best hands-on deep learning resource. The top-down teaching approach starts with building production models (image classification, NLP) in lesson 1, then progressively explains theory. Reddit users highlight "went from zero to Kaggle competitor in 7 weeks" and "finally understood transformers after fast.ai".

Key Features:

  • ✓Top-down teaching: build image classifier in lesson 1, then learn why it works
  • ✓fastai library abstracts PyTorch complexity while teaching best practices
  • ✓Free GPUs via Google Colab and Kaggle Notebooks (no local setup required)
  • ✓7-week course with 2-hour video lectures and Jupyter notebook exercises
  • ✓Covers CNNs, RNNs, transformers, GANs with practical applications
  • ✓Community forum with 50K+ members debugging code (course.fast.ai/forum)

Pricing:

Completely free

Pros:

  • + 180+ Reddit endorsements call it "best practical DL course" (r/MachineLearning top recommendation)
  • + Completely free with no upsells or paywalls (Jeremy Howard philosophy)
  • + Top-down approach lets you build projects immediately (Reddit: "motivation from day 1")
  • + Kaggle competition winners credit fast.ai for breakthroughs
  • + Works for coders without PhD (prerequisite: 1 year Python experience)

Cons:

  • - Requires coding experience (Reddit: "not for absolute beginners, do Python course first")
  • - fastai library hides details, can feel like "magic" until theory lessons (r/learnmachinelearning debate)
  • - Less structured than university courses, need self-discipline (Reddit: "easy to fall behind without deadlines")

Best For:

Developers with Python experience wanting hands-on deep learning without PhD math (r/MachineLearning consensus)

Try Practical Deep Learning for Coders (fast.ai) →
4

Deep Learning Specialization (Andrew Ng)

★4.9

Andrew Ng's Deep Learning Specialization earned 165+ Reddit mentions as the best structured path from neural networks to advanced architectures. The 5-course series covers CNNs (image recognition), RNNs (sequence models), transformers, and deployment. r/MachineLearning users cite "best explanation of backpropagation" and "TensorFlow assignments teach production skills".

Key Features:

  • ✓Neural Networks and Deep Learning: activation functions, gradient descent, vectorization
  • ✓CNNs for computer vision: ResNets, YOLO object detection, face recognition
  • ✓Sequence Models: RNNs, LSTMs, GRUs, attention mechanisms, transformers
  • ✓Hyperparameter tuning, batch normalization, optimization algorithms (Adam, RMSprop)
  • ✓TensorFlow 2 coding assignments with real datasets (hand sign recognition, sentiment analysis)
  • ✓5 courses (80 hours) with free audit or $49/month certificate

Pricing:

Free to audit, $49/month for certificate

Pros:

  • + 165+ Reddit mentions as best theoretical foundation (r/MachineLearning "gold standard")
  • + Andrew Ng explains calculus concepts visually without requiring math degree
  • + Structured progression: NNs → CNNs → RNNs → deployment (logical flow praised by r/learnmachinelearning)
  • + TensorFlow assignments prepare for industry (Reddit: "got ML engineer job after finishing")
  • + Free audit lets you learn without paying (certificate optional)

Cons:

  • - TensorFlow focus vs PyTorch industry trend (Reddit: "wish it taught PyTorch instead")
  • - Slower pace than fast.ai (80 hours vs 14 hours), less hands-on initially
  • - $49/month × 4-5 months = $200-250 if you need certificate (r/learnmachinelearning: "audit for free")

Best For:

Learners wanting structured deep learning theory with TensorFlow skills (Reddit: "best after Andrew Ng ML course")

Try Deep Learning Specialization (Andrew Ng) →
5

DataCamp AI Fundamentals / Machine Learning Scientist

★4.6

DataCamp's interactive AI tracks received 85+ Reddit mentions in r/learnmachinelearning for hands-on browser-based coding exercises. The Machine Learning Scientist track covers scikit-learn, supervised/unsupervised learning, and feature engineering through 15 courses (84 hours). Reddit users highlight "learned by doing, not just watching" and "projects helped portfolio".

Key Features:

  • ✓Interactive coding in browser (no local setup, runs Python in cloud)
  • ✓AI Fundamentals track: 6 courses covering ML basics, neural networks, ethics
  • ✓Machine Learning Scientist track: 15 courses (84 hours) with scikit-learn focus
  • ✓Hands-on projects: customer churn prediction, credit risk modeling, image classification
  • ✓14-day free trial (unlimited access) then $39/month or $149/year
  • ✓Mobile app for learning on commute (iOS/Android with offline mode)

Pricing:

$39/month or $149/year (14-day free trial)

Pros:

  • + 85+ Reddit recommendations for interactive learning (r/learnmachinelearning "best for beginners")
  • + No setup friction, code runs in browser immediately (Reddit: "started learning in 5 minutes")
  • + Affordable at $39/month vs bootcamps ($10K+) or Coursera certificates ($200+)
  • + 14-day trial lets you finish short courses for free (Reddit hack: "binge AI Fundamentals in trial")
  • + Certificate recognized by employers (DataCamp on LinkedIn)

Cons:

  • - Subscription model vs one-time Udemy courses (Reddit: "monthly fee adds up")
  • - Less theory than Andrew Ng (focus on coding not math, r/MachineLearning: "shallow understanding")
  • - Browser-based limits advanced projects (no GPU training, Reddit: "can't train large models")

Best For:

Beginners wanting affordable hands-on practice without setup complexity (Reddit: "best for career switchers")

Try DataCamp AI Fundamentals / Machine Learning Scientist →
6

CS229: Machine Learning (Stanford)

★4.9

Stanford's CS229 earned 95+ mentions in r/MachineLearning as the most rigorous free ML course. Taught by Andrew Ng (original) and now by other Stanford professors, the course dives deep into mathematical foundations, optimization theory, and probabilistic models. Reddit users note "PhD-level rigor" and "best for understanding the math behind algorithms".

Key Features:

  • ✓Linear algebra review, probability theory, multivariate calculus applications
  • ✓Supervised learning: linear regression, logistic regression, GLMs, SVMs, neural networks
  • ✓Unsupervised learning: K-means, GMMs, EM algorithm, PCA, ICA
  • ✓Reinforcement learning: MDPs, Q-learning, policy gradients
  • ✓Free lecture videos (20 × 1.5 hours), lecture notes, problem sets
  • ✓Stanford-level content accessible to anyone globally

Pricing:

Free (YouTube lectures + lecture notes)

Pros:

  • + 95+ Reddit mentions as most rigorous free course (r/MachineLearning "PhD preparation")
  • + Completely free (no paywalls, no certificates, pure learning)
  • + Mathematical depth exceeds Coursera (derives algorithms from first principles)
  • + Stanford credibility (taught by CS professors, same material as on-campus students)
  • + Self-paced via YouTube (watch 2x speed, rewind hard parts)

Cons:

  • - Requires strong math background (linear algebra, calculus, probability, Reddit: "not for beginners")
  • - No coding assignments in videos (Reddit: "watch CS229, code in Andrew Ng Coursera")
  • - Lecture notes assume Stanford undergrad knowledge (steep learning curve)

Best For:

Advanced learners with math background wanting deep theoretical understanding (Reddit: "after finishing Andrew Ng's courses")

Try CS229: Machine Learning (Stanford) →
7

Google AI Essentials

★4.5

Google's AI Essentials received frequent mentions in r/artificial for non-technical professionals wanting AI literacy. The course covers prompt engineering, AI ethics, and practical applications without coding. Reddit users highlight "explained AI to my marketing team" and "finished in one weekend".

Key Features:

  • ✓AI fundamentals: large language models, computer vision, generative AI explained simply
  • ✓Prompt engineering for ChatGPT, Gemini, and other LLMs
  • ✓AI ethics: bias, privacy, responsible AI principles
  • ✓Practical applications: content creation, data analysis, workflow automation
  • ✓Completely free with Google certificate upon completion
  • ✓6-hour course designed for busy professionals

Pricing:

Free

Pros:

  • + Free with no upsells (Google's contribution to AI education)
  • + Non-technical language (Reddit: "finally explained AI to my parents")
  • + Quick completion (6 hours) vs multi-month courses
  • + Google certificate adds credibility on LinkedIn
  • + Mobile-friendly for learning on commute

Cons:

  • - No coding or technical depth (Reddit: "great for managers, not engineers")
  • - Surface-level coverage (r/MachineLearning: "skip if you want to build AI")
  • - Certificate less valuable than Andrew Ng or DataCamp (Reddit job search discussions)

Best For:

Non-technical professionals needing AI literacy for work (Reddit: "best for product managers, marketers")

Try Google AI Essentials →
8

Python for Data Science and Machine Learning Bootcamp (Udemy)

★4.6

Jose Portilla's Udemy bootcamp earned 75+ mentions in r/learnmachinelearning as the most affordable hands-on ML course. The 25-hour course covers Python libraries (NumPy, pandas, matplotlib), scikit-learn, and ML algorithms through Jupyter notebooks. Reddit users cite "best project-based learning under $15" and "lifetime access beats subscriptions".

Key Features:

  • ✓Python crash course: NumPy, pandas, matplotlib, seaborn visualization
  • ✓Machine learning with scikit-learn: linear/logistic regression, decision trees, random forests, SVM
  • ✓Natural language processing: text classification, sentiment analysis
  • ✓Neural networks with TensorFlow basics
  • ✓100+ Jupyter notebook exercises and projects
  • ✓Lifetime access, one-time payment (vs monthly subscriptions)

Pricing:

$10-15 during sales (regular $99)

Pros:

  • + 75+ Reddit mentions for affordability (r/learnmachinelearning "best value")
  • + Udemy sales drop price to $10-15 (Reddit: "wait for sale, happens monthly")
  • + Lifetime access means you own the course forever
  • + Hands-on projects build portfolio (Reddit: "put Titanic survival predictor on GitHub")
  • + Beginner-friendly (no prerequisites beyond basic Python)

Cons:

  • - Less structured than Coursera (Reddit: "feels like watching YouTube tutorials")
  • - Jose Portilla not as famous as Andrew Ng (credibility gap)
  • - Udemy certificate has less weight (r/cscareerquestions: "employers prefer Coursera")

Best For:

Budget-conscious learners wanting hands-on ML practice (Reddit: "best under $20")

Try Python for Data Science and Machine Learning Bootcamp (Udemy) →
9

6.S191: Introduction to Deep Learning (MIT)

★4.7

MIT's 6.S191 course appears in 60+ r/MachineLearning threads as the best free deep learning course with cutting-edge content. Updated annually with latest research (2025 includes diffusion models, transformers, LLMs), the course provides lecture videos, TensorFlow labs, and guest lectures from industry. Reddit users note "covers latest AI trends" and "MIT quality for free".

Key Features:

  • ✓Deep learning foundations: neural networks, backpropagation, optimization
  • ✓CNNs for computer vision, RNNs for sequence modeling, transformers
  • ✓2025 updates: diffusion models (Stable Diffusion), LLMs (GPT architecture), RL with LLMs
  • ✓TensorFlow 2 lab assignments with Google Colab (free GPUs)
  • ✓Guest lectures from Google, OpenAI, Meta researchers
  • ✓Free lecture videos, slides, and code on GitHub

Pricing:

Free (lectures + labs)

Pros:

  • + 60+ Reddit mentions for staying current (r/MachineLearning "most up-to-date free course")
  • + MIT credibility (same content as on-campus students)
  • + Completely free with no paywalls
  • + Annual updates include latest AI research (2025 diffusion models, LLMs)
  • + Guest lectures from industry leaders provide real-world insights

Cons:

  • - Fast-paced for beginners (Reddit: "assumes you know Python and calculus")
  • - No certificate or credential (MIT doesn't offer one for free version)
  • - Shorter than full courses (7 lectures vs Andrew Ng's 80 hours)

Best For:

Intermediate learners wanting cutting-edge deep learning knowledge (Reddit: "after Andrew Ng DL course")

Try 6.S191: Introduction to Deep Learning (MIT) →
10

Elements of AI (University of Helsinki)

★4.6

University of Helsinki's Elements of AI received mentions in r/artificial for accessible AI education without math or coding. The course covers AI history, machine learning concepts, neural networks, and societal implications through interactive exercises. Reddit users highlight "explained AI to non-technical friends" and "Finland's gift to the world".

Key Features:

  • ✓AI history: Turing test, expert systems, AI winters
  • ✓Machine learning basics: supervised vs unsupervised, overfitting, model evaluation
  • ✓Neural networks explained visually without calculus
  • ✓AI ethics: bias in algorithms, job displacement, privacy
  • ✓Interactive exercises with instant feedback
  • ✓Free certificate upon completion (6 weeks, 5 hours/week)

Pricing:

Free

Pros:

  • + Completely free with certificate (no hidden costs)
  • + No prerequisites (Reddit: "taught AI to my 60-year-old mom")
  • + Visual explanations make complex concepts accessible
  • + Covers ethics and societal impact (often ignored in technical courses)
  • + Mobile-friendly for bite-sized learning

Cons:

  • - No coding or hands-on projects (Reddit: "good overview, but can't build anything")
  • - Superficial coverage (r/MachineLearning: "too basic for developers")
  • - Certificate has less recognition than Coursera or DataCamp

Best For:

Complete beginners wanting AI literacy without technical commitment (Reddit: "perfect first course")

Try Elements of AI (University of Helsinki) →
11

Hugging Face NLP Course

★4.7

Hugging Face's NLP course earned mentions in r/MachineLearning and r/LanguageTechnology for hands-on transformer training. The course teaches BERT, GPT, T5, and other models using the transformers library (industry standard for NLP). Reddit users cite "best for understanding ChatGPT architecture" and "got NLP job after finishing".

Key Features:

  • ✓Transformer architecture: attention mechanisms, positional encoding, encoder-decoder
  • ✓Hugging Face transformers library: BERT, GPT-2, T5, DistilBERT
  • ✓Fine-tuning pre-trained models on custom datasets
  • ✓Text classification, named entity recognition, question answering, summarization
  • ✓Free access to GPUs via Google Colab integration
  • ✓Community forum with Hugging Face engineers answering questions

Pricing:

Free

Pros:

  • + Free with no paywalls (Hugging Face open-source philosophy)
  • + Industry-relevant skills (transformers library used at Google, Meta, OpenAI)
  • + Hands-on fine-tuning beats theory-only courses (Reddit: "actually built a chatbot")
  • + Up-to-date with latest models (2025 includes Llama 3, Mistral)
  • + Strong community support (Hugging Face Discord + forum)

Cons:

  • - Assumes deep learning knowledge (Reddit: "do Andrew Ng DL first")
  • - No certificate or credential (pure learning, no resume boost)
  • - NLP-specific, doesn't cover computer vision or RL

Best For:

Developers wanting NLP/LLM skills for modern AI applications (Reddit: "essential for ChatGPT-style projects")

Try Hugging Face NLP Course →
12

ChatGPT Prompt Engineering for Developers (DeepLearning.AI)

★4.8

DeepLearning.AI's prompt engineering course received mentions in r/ChatGPT and r/OpenAI for teaching API usage. The 1-hour course covers prompt design patterns, summarization, inference, and transformation using OpenAI API. Reddit users highlight "learned prompting in an afternoon" and "got API skills for job".

Key Features:

  • ✓Prompt engineering principles: clear instructions, few-shot learning, chain-of-thought
  • ✓OpenAI API coding: text generation, summarization, sentiment analysis
  • ✓Iterative prompt refinement techniques
  • ✓Building LLM applications: chatbots, summarizers, translators
  • ✓Free 1-hour course with hands-on Jupyter notebooks
  • ✓Taught by Andrew Ng and OpenAI engineers

Pricing:

Free

Pros:

  • + Free and quick (1 hour vs multi-week courses)
  • + Directly applicable to ChatGPT API projects (Reddit: "started building same day")
  • + Taught by Andrew Ng and OpenAI team (credibility)
  • + Hands-on coding vs theory-only courses
  • + Certificate upon completion (add to LinkedIn)

Cons:

  • - Very short, lacks depth (Reddit: "good intro, not comprehensive")
  • - OpenAI API costs money for actual projects (free tier limited)
  • - Focused on OpenAI, doesn't cover Anthropic Claude or other APIs

Best For:

Developers wanting quick LLM API skills (Reddit: "best 1-hour time investment")

Try ChatGPT Prompt Engineering for Developers (DeepLearning.AI) →

Frequently Asked Questions

Reddit communities recommend Andrew Ng's Machine Learning Specialization (245+ mentions in r/MachineLearning) for complete beginners. The course requires no math background beyond high school algebra and teaches supervised learning, neural networks, and unsupervised learning through Python. The free audit option on Coursera lets you access all content without paying. Alternative free options include Google AI Essentials (6 hours, non-technical) and Elements of AI from University of Helsinki (interactive exercises, no coding). Avoid jumping directly into fast.ai or Stanford CS229 without foundational knowledge, as Reddit users report "too steep for absolute beginners".

Choose Your AI Learning Path Based on Goals

Reddit's 500+ r/MachineLearning threads reveal two optimal learning paths for 2026. Beginners seeking AI literacy should start with Andrew Ng's Machine Learning Specialization (free Coursera audit, 245+ mentions), add Google AI Essentials (free, 6 hours) for non-technical context, and progress to Andrew Ng's Deep Learning Specialization (165+ mentions) for neural network foundations. Technical learners building AI systems should combine Andrew Ng ML course for theory with fast.ai Practical Deep Learning (180+ mentions, free) for hands-on PyTorch projects, supplement with Stanford CS229 on YouTube (95+ mentions, free) for mathematical depth, and specialize via Hugging Face NLP Course (free) for language models or MIT 6.S191 (60+ mentions, free annual updates) for cutting-edge research. DataCamp offers structured interactive learning at $39/month with 14-day trials for trying courses risk-free. Udemy courses drop to $10-15 during monthly sales for one-time affordable purchases. All paths benefit from Kaggle competitions for practice and GitHub portfolios for demonstrating skills to employers. The r/learnmachinelearning consensus emphasizes "avoid course purgatory" by limiting foundational learning to 3-6 months before building projects, as Reddit job seekers report "projects and coding interviews matter more than certificates". Free options (fast.ai, CS229, MIT 6.S191) provide equivalent knowledge to paid courses, with paid certificates adding resume credibility but not replacing hands-on skills.

Non-technical? Start with Udemy AI for Everyone (one-time payment, no coding needed). Technical? Audit Andrew Ng ML on Coursera for free. Either way, join r/learnmachinelearning for community support.

About the Author

Amara - AI Tools Expert

Amara

Amara is an AI tools expert who has tested over 1,800 AI tools since 2022. She specializes in helping businesses and individuals discover the right AI solutions for text generation, image creation, video production, and automation. Her reviews are based on hands-on testing and real-world use cases, ensuring honest and practical recommendations.

View full author bio→

Related Guides

Best AI Tools: Top Picks from Reddit Communities [2026]

Discover the best AI tools recommended by Reddit communities in 2026. Based on 4M+ r/ChatGPT members, r/ArtificialIntelligence insights, and real user reviews. Expert guide.

Best AI for Coding: Reddit's Top Picks for Developers [2026]

Best AI coding assistants per Reddit developers in 2026. Claude Opus 4.6 vs GitHub Copilot vs Cursor vs Codeium compared by r/programming and r/learnprogramming communities.

ChatGPT for Students: Reddit's Best Study Hacks, Prompts & Ethical Use Guide [2026]

Discover how students use ChatGPT ethically from r/college, r/students, r/ChatGPT (4M+ members). Top study workflows, prompting strategies, GPT-5.2 vs free tier, academic integrity guidelines, and alternatives.

Best AI Apps According to Reddit: Real User Recommendations from 2026

Reddit users recommend ChatGPT, Descript, Gamma, and Fireflies as the best AI apps in 2026. Real reviews from 4M+ members across r/ChatGPT, r/productivity, and r/ArtificialIntelligence.