Lessons from Stanford CS336
Why Understanding the Foundations Matters in the Age of Frontier Models
The Stanford CS336 course, "Large Language Models," takes a bold and refreshing stance in today’s AI landscape: to truly understand large language models (LLMs), you have to build them from scratch.
This approach isn’t just about education. It’s about mastery, innovation, and reclaiming agency in a world increasingly dominated by proprietary AI. Through a hands-on curriculum, students recreate the full LLM pipeline—from raw text to token generation—gaining not only technical depth but a mindset of efficiency and rigor that mirrors the philosophy behind today's most powerful models.
The Five Pillars of Building LLMs from Scratch
1. Basics: From Token to Transformer
The journey starts by implementing the core model mechanics:
Tokenizer: A Byte Pair Encoding (BPE) tokenizer is built from scratch, translating raw text into integer token sequences. While tokenizer-free methods are emerging, BPE remains a staple of frontier models.
Transformer Architecture: Students code the original "Attention is All You Need" architecture, then explore modern enhancements like rotary embeddings and advanced normalization layers.
Training Loop: They implement cross-entropy loss, AdamW optimizer, and a full training loop—all from first principles.
Deliverable: A functioning mini-LLM, trained on a small dataset using nothing but foundational PyTorch components.
2. Systems: Optimizing for Hardware Efficiency
With the basics working, attention turns to GPU and systems-level performance:
Kernels and Memory Bandwidth: Using Triton, students build custom GPU kernels and apply techniques like fusion and tiling to reduce data movement.
Parallelism: Concepts like tensor parallelism and pipeline parallelism are explored to distribute training across multiple GPUs.
Inference Optimization: Students learn to distinguish between prefill (parallelizable) and decode (sequential), and apply speculative decoding to accelerate generation.
Takeaway: Profiling and benchmarking become second nature. You can't improve what you don't measure.
3. Scaling Laws: Predicting Performance at Scale
This pillar focuses on how small-scale experiments can inform large-scale model design:
Data vs. Model Size: Students learn to balance training dataset size with model parameter count under a fixed compute budget.
Chinchilla Scaling Laws: The idea that smaller models trained longer can outperform larger models trained briefly is explored.
Curve Fitting: They fit empirical scaling curves to predict optimal hyperparameters.
Mindset: Every experiment costs compute. Think like a frontier lab: test smart, scale efficiently.
4. Data: The Backbone of Quality
Far from being a passive ingredient, data is a central differentiator:
Curation: Training data is collected from books, websites, code, and more, then rigorously filtered and deduplicated.
Preprocessing: Converting messy HTML or PDFs into clean, structured text is a critical skill.
Evaluation: Model performance is judged using perplexity, benchmark tasks (e.g., MMLU), and instruction-following tests.
Note: Legal and ethical considerations are always in scope.
5. Alignment: Making Models Helpful and Safe
Finally, the base model is tuned to be useful, polite, and safe:
Supervised Fine-Tuning (SFT): A dataset of prompt-response pairs teaches the model instruction-following behavior.
Learning from Feedback (LfF): More advanced tuning uses preference data and verifiers, with methods like DPO and GRPO.
Goal: Turn raw potential into aligned performance through iterative feedback and safety-driven training.
Why This Approach Matters
Deep Understanding: Rather than treating models as black boxes, students understand every layer and why it matters.
Design Intuition: By implementing everything manually, they gain insight into trade-offs and design decisions.
Efficiency Mindset: With limited resources, they learn to optimize like OpenAI and DeepMind teams.
Path to Leadership: This is the training ground for tomorrow’s AI researchers, engineers, and startup founders.
A Word on Limitations
While the models built in this course are small, the lessons are scalable. You won’t match GPT-4’s capability, but you will:
Understand the architecture that makes it work
Gain the skills to build better small-scale models
Learn the mindset needed to contribute to the future of open, responsible AI
Final Thoughts
Building LLMs from scratch is more than an academic exercise. It’s a powerful act of understanding and empowerment. The frontier may be out of reach for now, but the mindset and skills required to get there start here.
If you’re serious about AI, don’t just prompt models.
Build them.
AI Fundamentals Recap
Think of AI as the broad goal of making computers do things that normally require human intelligence. This could be anything from making decisions, solving problems, understanding speech, or even learning new things. It's like trying to build a "smart" machine.
Machine Learning is a way to achieve Artificial Intelligence. Instead of programming a computer with exact instructions for every single task, ML allows computers to learn from data. Imagine showing a computer thousands of pictures of cats. Eventually, it learns to recognize a cat on its own, without you describing "pointy ears" or "whiskers" in code. It finds patterns in the examples.
LLMs are a specific type of Machine Learning model that's really good with human language (text). The "Large" part means they've been trained on enormous amounts of text data—think of them as having read a huge chunk of the internet, books, and articles.
They work by learning to predict the next word in a sentence. By doing this over and over on massive datasets, they learn grammar, context, facts, and even how to reason or be creative with text.
Popular examples you might have heard of include models like ChatGPT. They can write emails, answer questions, summarize articles, translate languages, and even help write computer code.
With these basic ideas in mind, the blog post "Beyond Bigger: How LLMs Are Evolving and Revolutionizing Engineering" will make more sense as it discusses the latest advancements in these language-focused AI systems and how they're being applied in practical ways. Enjoy the read!
Timeline of Large Language Model Evolution
Beyond Bigger: How LLMs Are Evolving and Revolutionizing Engineering
The world of Large Language Models (LLMs) is moving at breakneck speed. Not long ago, the mantra was simply "bigger is better." While scale laid the foundation, the current trajectory of LLMs is far more nuanced and exciting. We're witnessing a shift from brute-force scaling to smarter architectures, sophisticated reasoning techniques, and a rapidly expanding toolkit of capabilities. This evolution isn't just an academic curiosity; it's unlocking powerful new applications across industries, with engineering poised for a particularly profound transformation.
Forget the notion of LLMs hitting a performance ceiling. Instead, think of it as a field branching out, finding new avenues for growth and impact. Let's explore how LLMs are evolving and what this means for the future of engineering.
From Raw Scale to Intelligent Design: The Architectural Shift
The journey started with the groundbreaking Transformer architecture and the realization that increasing model size, data, and compute power led to predictable performance gains. This was crucial, but the story doesn't end there.
Smarter Scaling: Landmark research like DeepMind's Chinchilla scaling laws brought a more refined understanding: it's not just about size, but the optimal ratio of parameters and training tokens. This led to more compute-efficient models, and a realization that earlier giants might have been undertrained. The focus now includes optimizing for inference costs, meaning models like Llama 3 are trained on vastly more data per parameter, making them more efficient to run in real-world applications.
The Rise of MoE: A significant architectural leap is the Mixture of Experts (MoE) model. Imagine a team of specialists instead of one generalist. MoE models comprise numerous "expert" sub-networks and a "router" that directs input tokens to the most relevant experts. This allows for a dramatic increase in total model parameters (think hundreds of billions, or even trillions) without a proportional surge in computational cost per token. The result? Faster training and inference, paving the way for even more powerful and responsive models. Many of today's leading LLMs are believed to incorporate MoE layers.
Not Just Bigger, But Smarter: Advanced Reasoning at Inference
Some of the most exciting progress isn't just about how models are built, but how we interact with them and elicit more sophisticated responses during inference (when the model is actually generating output).
In-Context Learning (ICL): The magic of providing a few examples in a prompt (few-shot prompting) to guide the LLM to perform a new task without any retraining remains a cornerstone.
Chain of Thought (CoT) Prompting: This has been a game-changer. By prompting the LLM to "think step by step" or providing examples of reasoned-out answers, we unlock significantly better performance on complex tasks requiring logical deduction, math, and common sense. It’s like asking the model to show its work, leading to more accurate and transparent outputs. Variations like Self-Consistency (generating multiple reasoning chains and taking a majority vote) and Tree of Thought (exploring multiple reasoning pathways) are pushing these boundaries further, albeit with increased computational cost.
Leveraging Emergent Abilities: These advanced inference techniques tap into the "emergent abilities"—capabilities like ICL and instruction following that appear as models scale—to unlock new levels of performance even without altering the model's weights.
Expanding Horizons: New Capabilities and Frontiers
The evolution extends beyond core text processing and reasoning into entirely new domains of interaction and application:
Grounding with RAG: Retrieval Augmented Generation (RAG) is a powerful technique connecting LLMs to external, up-to-date knowledge bases. By retrieving relevant information from vast document repositories (like technical manuals or research papers) and feeding it to the LLM along with the user's query, RAG helps combat outdated training data, reduce hallucinations, and provide factually grounded, domain-specific answers.
The Dawn of LLM Agents: This is a major frontier. LLM Agents are systems that use an LLM as a central "brain" to autonomously plan, make decisions, use tools (like APIs, code interpreters, or even other models), and interact with their environment to achieve complex, multi-step goals. This moves far beyond simple prompt-and-response to active, intelligent problem-solving.
Seeing and Hearing: Multimodal LLMs (MLLMs): The world isn't just text, and neither are the next generation of LLMs. MLLMs are designed to process, understand, and generate information across multiple modalities—text, images, audio, and even video. This opens up intuitive new ways to interact with AI and tackle problems that require understanding diverse data types.
Refined Training for Alignment: The journey from a raw foundation model to a helpful, harmless, and honest AI assistant involves crucial post-training steps. Supervised Fine-tuning (SFT) adapts models to specific tasks, while Reinforcement Learning from Human Feedback (RLHF) aligns model outputs with human preferences and values, significantly enhancing their quality and usefulness.
Glimpsing the Future: Researchers are already exploring even more fundamental shifts, such as training models to predict abstract representations or semantic concepts directly, potentially moving beyond the limitations of next-token prediction.
The Engineering Revolution: LLMs in Action
These advancements are not just theoretical; they are actively being harnessed to transform engineering disciplines:
Accelerated R&D and Knowledge Discovery with RAG:
Engineers can query vast internal databases of past project reports, research papers, material specifications, and compliance documents instantly.
Application: Quickly finding solutions to recurring design challenges, identifying relevant patents, or ensuring new designs comply with the latest standards.
Imagine an aerospace engineer using RAG to access decades of material science data and flight test reports to select the optimal alloy for a new component, all while cross-referencing the latest FAA regulations.
Complex Problem Solving & Design with CoT:
Chain of Thought and its advanced variants can guide LLMs through complex engineering calculations, diagnostic procedures, and system design trade-offs.
Application: Debugging intricate software, performing root cause analysis for hardware failures, generating and evaluating multiple design options based on constraints, or even drafting initial mathematical models for physical phenomena.
A chemical engineer could use CoT to troubleshoot an unexpected drop in yield in a production process, with the LLM reasoning through potential causes from sensor data and chemical pathway knowledge.
Automating and Optimizing with LLM Agents:
LLM Agents can automate repetitive design tasks, run simulations, manage project workflows by interacting with project management software, or even control robotic systems for fabrication or inspection.
Application: An agent could monitor a construction site via sensor data, flag potential safety issues, and automatically update project timelines. Another could generate and test multiple variations of a circuit design, optimizing for power consumption and performance.
Software engineers are already benefiting from agents that can write, debug, and test code (as seen in benchmarks like SWEBench), a capability increasingly valuable for scripting and automation in all engineering fields.
Enhanced Design and Analysis with Multimodal LLMs:
MLLMs can interpret technical drawings, analyze images from inspections (e.g., identifying cracks in a structure), or understand spoken instructions alongside textual specifications.
Application: Generating a 3D model from a 2D sketch and textual description, automatically creating documentation by "seeing" a physical prototype, or allowing field engineers to report issues using voice and images, which are then translated into structured reports.
A civil engineer could use an MLLM to analyze drone footage of a bridge, combined with sensor data, to assess structural integrity and generate an inspection report with visual annotations.
Specialized Engineering Assistants through Fine-tuning:
By fine-tuning base LLMs on domain-specific engineering textbooks, codes, and proprietary data (using SFT and RLHF), companies can create expert assistants tailored to their unique needs.
Application: An electrical engineer having a dedicated LLM fine-tuned on IEEE standards and semiconductor physics, or a biotech engineer with an assistant trained on genomic data and lab protocols. This ensures higher accuracy, relevance, and safety in specialized contexts.
Advanced STEM Reasoning (GPQA Benchmark):
Models are increasingly being tested on graduate-level STEM questions, indicating their growing capacity to tackle truly deep and complex engineering challenges that require advanced reasoning.
The Path Forward
The trajectory of LLMs is clear: they are becoming more capable, more efficient, more versatile, and critically, more integratable into complex workflows. While challenges remain in areas like robust long-range planning for agents, ensuring complete factual accuracy, and addressing ethical considerations, the pace of innovation is staggering.
For the engineering world, this means we are on the cusp of a new era. These evolving AI tools will not replace engineers but will augment their capabilities, automate tedious tasks, unlock new design paradigms, and ultimately allow human ingenuity to focus on higher-level challenges. The future of engineering will be a collaborative one, where human expertise is amplified by increasingly intelligent and versatile LLMs. The journey is just beginning, and the potential is immense.