A deep understanding of AI large language model mechanisms (Udemy.com)
Build and train LLM NLP transformers and attention mechanisms (PyTorch). Explore with mechanistic interpretability tools
Created by: Mike X Cohen
Last updated August 2026
Our take
Based on the ratings of 1,415 students, a sample of their written reviews and the syllabus, as the course stood in August 2026. No course pays to be reviewed.
This is a huge, code-heavy course on how large language models work inside. It runs about 91 hours across 329 lectures. The first parts cover tokenization, embeddings, building a GPT, pretraining, fine-tuning and instruction tuning. Then it moves to evaluation, AI safety, and a long stretch of mechanistic interpretability, where students study neurons, layers and circuits and then edit activations. It is not a casual intro. Mike X Cohen, a former neuroscience professor, teaches it, and a Python tutorial and a deep learning intro sit at the end.
Reviewers like the teaching a lot. They mention clear explanations, an easy pace, humor and a strong sense of rapport, and several say they have taken his other courses and rate this one highly. The code challenges get praise too, though one reviewer notes the helper files do a good deal of the thinking, which real projects will not. The main complaint is size. One five-star reviewer asks for a split into two courses, basic architecture and interpretability, because finishing it all is close to impossible. Another warns it is not for absolute beginners.
The numbers back the praise: 4.8 from 1,415 ratings, with about 73 percent giving five stars and only seven giving one or two. More than 20,000 students have enrolled, and the last update was in August 2026, so it is current. The listing shows no quizzes. If you want to understand and tinker with transformers, the hours are well spent. If you only need to use LLMs, pick something shorter, and treat this one as a long project done in pieces.
Pros
- Builds a GPT in PyTorch step by step, then pretrains and fine-tunes it
- Teaching is praised as clear, easy paced and humorous, with real rapport
- Long interpretability section covers neurons, layers, circuits and editing activations
- Updated in August 2026, and a reviewer calls it up to date
Cons
- About 91 hours is hard to finish; one reviewer wants it split in two
- Not for absolute beginners, despite the All Levels label
- Helper files give away part of the problem solving, one reviewer says
I have been learning from Mike for years and have taken his other courses. He has a gift for teaching and this is his best work yet! clear explanations, up to date, covers the fundamentals and is easy paced.
Listed as All Levels, but reviewers say it is not for beginners. The requirements call basic linear algebra and some ML helpful.
What you will learn
- Large language model (LLM) architectures, including GPT (OpenAI) and BERT
- Transformer blocks
- Attention algorithm
- Pytorch
- LLM pretraining
- Explainable AI
- Mechanistic interpretability
- Machine learning
- Deep learning
- Principal components analysis
- High-dimensional clustering
- Dimension reduction
- Advanced cosine similarity applications
Course content
40 sections · 329 lectures · 91 hours of video 9 articles
- 1Introductions 3 free previews5 lectures · 44 min
- 2—— ** —— Part 1: Tokenizations and embeddings —— ** ——1 lecture
- 3Words to tokens to numbers 1 free preview22 lectures · 5.2 hours
- 4Embeddings spaces 1 free preview18 lectures · 6.6 hours
- 5—— ** —— Part 2: Large language models —— ** ——1 lecture
- 6Build a GPT 1 free preview29 lectures · 8.4 hours
- 7Pretrain LLMs 1 free preview20 lectures · 5.2 hours
- 8Fine-tune pretrained models 1 free preview24 lectures · 6.2 hours
- 9Instruction tuning7 lectures · 1.6 hours
- 10—— ** —— Part 3: Evaluating LLMs —— ** ——1 lecture
- 11Quantitative evaluations 1 free preview15 lectures · 3.5 hours
- 12Qualitative evaluations 1 free preview6 lectures · 1.4 hours
- 13—— ** —— Part 4: AI safety and mechanistic interpretability —— ** ——1 lecture · 1 min
- 14AI safety6 lectures · 53 min
- 15Interpretability5 lectures · 56 min
- 16—— ** —— Part 5: Observation (non-causal) mech interp —— ** ——1 lecture
- 17Investigating token embeddings (part 1) 1 free preview22 lectures · 6.7 hours
- 18Investigating neurons and dimensions 1 free preview23 lectures · 7.2 hours
- 19Investigating layers 1 free preview17 lectures · 6.4 hours
- 20Investigating token embeddings (part 2) 1 free preview9 lectures · 3.2 hours
- 21Identifying circuits and components 1 free preview14 lectures · 6.7 hours
- 22—— ** —— Part 6: Intervention (causal) mech interp —— ** ——1 lecture
- 23How to modify activations 1 free preview3 lectures · 1 hour
- 24Editing hidden states6 lectures · 2.2 hours
- 25Interfering with attention 1 free preview7 lectures · 2.6 hours
- 26Modifying MLP4 lectures · 2 hours
- 27—— ** —— Part 7: Python tutorial —— ** ——1 lecture
- 28Python intro: Colab and notebooks1 lecture · 16 min
- 29Python intro: Data types5 lectures · 1 hour
- 30Python intro: Indexing and slicing2 lectures · 23 min
- 31Python intro: Functions6 lectures · 1.1 hours
- 32Python intro: Flow control6 lectures · 1.1 hours
- 33Python intro: Data visualization3 lectures · 36 min
- 34Python intro: Strings and texts3 lectures · 23 min
- 35Python intro: Pytorch5 lectures · 52 min
- 36—— ** —— Part 8: Deep learning intro —— ** ——1 lecture
- 37Math of deep learning15 lectures · 3.4 hours
- 38How models learn: gradient descent5 lectures · 1.2 hours
- 39Essence of deep learning modeling7 lectures · 1.9 hours
- 40Bonus content1 lecture
Who it is for
The instructor says it suits
- AI engineers
- Scientists interested in modern autoregressive modeling
- Natural language processing enthusiasts
- Students in a machine-learning or data science course
- Graduate students or self-learners
- Undergraduates interested in large language models
- Machine-learning or data science practitioners
- Researchers in explainable AI
What you need before you start
- Motivation to learn about large language models and AI
- Experience with coding is helpful but not necessary
- Familiarity with machine learning is helpful but not necessary
- Basic linear algebra is helpful
- Deep learning, including gradient descent, is helpful but not necessary
How it compares
Against the other 503 rated Udemy courses in Teaching & Academics on CourseDuck:
- Rating4.8 out of 5higher than 87% of them
- Reviews1,415#115 of 504 by number of reviews
- Length91 hourslonger than 99% of them
- Last updatedAugust 2026more recently than 92% of them
Course Description
Deep Understanding of Large Language Models (LLMs): Architecture, Training, and Mechanisms
Description
Large Language Models (LLMs) like ChatGPT, GPT-4, , GPT5, Claude, Gemini, and LLaMA are transforming artificial intelligence, natural language processing (NLP), and machine learning. But most courses only teach you how to use LLMs. This 90+ hour intensive course teaches you how they actually work — and how to dissect them using machine-learning and mechanistic interpretability methods.
This is a deep, end-to-end exploration of transformer architectures, self-attention mechanisms, embeddings layers, training pipelines, and inference strategies — with hands-on Python and PyTorch code at every step.
Whether your goal is to build your own transformer from scratch, fine-tune existing models, or understand the mathematics and engineering behind state-of-the-art generative AI, this course will give you the foundation and tools you need.
What You’ll Learn
The complete architecture of LLMs — tokenization, embeddings, encoders, decoders, attention heads, feedforward networks, and layer normalization
Mathematics of attention mechanisms — dot-product attention, multi-head attention, positional encoding, causal masking, probabilistic token selection
Training LLMs — optimization (Adam, AdamW), loss functions, gradient accumulation, batch processing, learning-rate schedulers, regularization (L1, L2, decorrelation), gradient clipping
Fine-tuning and prompt engineering for downstream NLP tasks, system-tuning
Evaluation metrics — perplexity, accuracy, and benchmark datasets such as MAUVE, HellaSwag, SuperGLUE, and ways to assess bias and fairness
Practical PyTorch implementations of transformers, attention layers, and language model training loops, custom classes, custom loss functions
Inference techniques — greedy decoding, beam search, top-k sampling, temperature scaling
Scaling laws and trade-offs between model size, training data, and performance
Limitations and biases in LLMs — interpretability, ethical considerations, and responsible AI
Decoder-only transformers
Embeddings, including token embeddings and positional embeddings
Sampling techniques — methods for generating new text, including top-p, top-k, multinomial, and greedy
Why This Course Is Different
93+ hours of HD video lectures — blending theory, code, and practical application
Code challenges in every section — with full, downloadable solutions
Builds from first principles — starting from basic Python/Numpy implementations and progressing to full PyTorch LLMs
Suitable for researchers, engineers, and advanced learners who want to go beyond “black box” API usage
Clear explanations without dumbing down the content — intensive but approachable
Who Is This Course For?
Machine learning engineers and data scientists
AI researchers and NLP specialists
Software developers interested in deep learning and generative AI
Graduate students or self-learners with intermediate Python skills and basic ML knowledge
Technologies & Tools Covered
Python and PyTorch for deep learning
NumPy and Matplotlib for numerical computing and visualization
Google Colab for free GPU access
Hugging Face Transformers for working with pre-trained models
Tokenizers and text preprocessing tools
Implement Transformers in PyTorch, fine-tune LLMs, decode with attention mechanisms, and probe model internals
What if you have questions about the material?
This course has a Q&A (question and answer) section where you can post your questions about the course material (about the maths, statistics, coding, or machine learning aspects). I try to answer all questions within a day. You can also see all other questions and answers, which really improves how much you can learn! And you can contribute to the Q&A by posting to ongoing discussions.
By the end of this course, you won’t just know how to work with LLMs — you’ll understand why they work the way they do, and be able to design, train, evaluate, and deploy your own transformer-based language models.
Enroll now and start mastering Large Language Models from the ground up.
Instructor Details
- 4.8 Rating
1,415 Reviews
Mike X Cohen
I am a full-time educator and writer, and former professor of neuroscience. I "retired" from that position so I could focus my time and energy creating high-quality educational material just for you.
I have 20 years of experience teaching programming, data analysis, signal processing, statistics, linear algebra, and experiment design. I've taught undergraduate students, PhD candidates, postdoctoral researchers, and full professors. I have taught in "traditional" university courses, special week-long intensive courses, and Nobel prize-winning research labs. I have >100 hours of online lectures on neuroscience data analysis that you can find on my website and youtube channel. And I've written several technical books about these topics with a few more on the way.
I'm not trying to show off -- I'm trying to convince you that you've come to the right place to maximize your learning from an instructor who has spent two decades refining and perfecting his teaching style.
Over 350,000 students have watched over 50,000,000 minutes of my courses. Come find out why!
I have several free courses that you can enroll in. Try them out! You got nothing to lose ;)
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Reviews
By Ludovico Saint Amour Di Chanaz on 7/29/2026
I'm learning plenty. I have interacted with Mike before during my PhD in neurosciences and followed in his footsteps in the world of AI, and he's just as brilliant in AI as he is in Neurosciences. This is bliss.
By Nicolas Kentepotsidis on 5/28/2026
The helper files are great! Of course, they are solutioning a great deal of the problem and making the thought process we need to do much easier. In real life, it's not like that.
By Danish on 5/7/2026
I have been learning from Mike for years and have taken his other courses. He has a gift for teaching and this is his best work yet! clear explanations, up to date, covers the fundamentals and is easy paced. Please keep it updated Mike!
By Joshua Riley on 4/12/2026
The depth of the course is exactly what I needed to expand my research career. As someone who focused on RL, MARL, Safety, etc, it was great to have a course go into the practical and theoretical steps I needed to transition into Transformers.
By Wang Leong Wong on 4/10/2026
I should have learnt a lot from the course. The presentation was impressive when I watched the very first lectures. The treasurable parts of the course should be its extensive analysis and experiments. BTW, how do we probe our brain? fMRI?
By Yong Choi on 3/26/2026
I've enrolled in several of Mike's courses before, and this one upholds the same high standard. He explains LLM concepts clearly and progressively, and the coding challenges ensure students get meaningful hands-on practice. I truly appreciate his commitment to teaching.
By CLEMENT on 3/13/2026
So far very good explanations for a beginner like me. I like very much the python examples.
By Stancho Stanchev on 2/14/2026
Great course ! Concepts are well explained, along with Python code. You really will start to understand language models.
By Abhigyan Datta on 1/14/2026
It is the first course anyone wishing to learn about LLMs or aiming to become AI engineer should take. Mike's a fantastic educator, and keeps the lessons engaging and fun with lots of coding preactice.
By Rob Hubert on 1/6/2026
I've taken dozens of courses from Udemy over several years and this is truly one of the best and most comprehensive The instructor is able to deliver highly complex topics in understandable terms.
Quality Score
No CourseDuck member has rated this course yet. Taken it? Give each part a thumbs up or down.
Overall Score : 96 / 100












