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tech 7 June 2026

How LLMs Actually Work

Dive into the workings of modern LLMs. Understand how transformers, multi-head attention, and tokenization turn text into intelligent predictions.

Article inspired by the original source
How LLMs Actually Work ↗ 0xkato.xyz

# How LLMs Actually Work

Large Language Models (LLMs) are at the forefront of today's AI technological revolutions. They enable text generation, answer questions, and even engage in complex conversations. But how do these models really work? In this article, we'll explore the essential components of LLMs, primarily based on transformers, without diving into complex mathematical details. We'll cover tokenization, embeddings, positional encoding, and more.

Tokenization: From Text to Integers

LLMs don't read words like we do. They convert texts into sequences of integers, a crucial step known as tokenization. For example, the word "tokenization" might be split into ["token", "ization"]. This sub-word approach balances efficiency and the model's ability to generalize. A typical LLM vocabulary contains between 30,000 and 100,000 entries, each word represented by a unique ID.

Embeddings: Giving Meaning to Integers

Once tokens are generated, they need to be meaningful to the model. This is where embeddings come into play. They transform integer IDs into vectors of real numbers that capture semantic relationships between words. For example, the words "king" and "queen" will have similar embeddings, indicating a close conceptual relationship.

Positional Encoding: Keeping Order

Transformers have no inherent notion of word order. Positional encoding solves this by adding positional information to embeddings. This allows the model to differentiate "the cat eats the fish" from "the fish eats the cat".

Attention Mechanism: Sharing Information

Attention is a central component of LLMs. It allows the model to focus on different parts of the text based on context. For instance, in the sentence "She gave the book to Peter because he asked for it", attention helps determine that "he" refers to "Peter".

Multi-Head Attention: Tracking Multiple Relationships

To capture complex relationships, LLMs use multi-head attention. Each attention head tracks different types of relationships between words, such as syntactical or semantic relationships. This enriches the model's understanding and improves its predictions.

Feed-Forward Network: Storing Structure

After attention, data passes through a feed-forward network, a dense layer that further refines the representations. This is where much of the LLM's power resides.

Layer Normalization and Residual Stream: Facilitating Learning

To train deep networks, layer normalization and residual connections are essential. They ensure learning stability and help avoid gradient problems.

Predicting the Next Token: The Heart of Generation

Finally, the model predicts the next token in a sequence, generating coherent and relevant text. This prediction loop is what allows LLMs to create content fluently.

Differences between Architecture and Trained Weights

While the structure of LLMs is largely shared, trained weights vary depending on the model and training data. These differences influence the model's performance and capabilities.

In conclusion, understanding how LLMs work is crucial for leveraging their potential in developing advanced AI solutions. Let's discuss your project in 15 minutes.

LLMs Transformers Tokenization Multi-head Attention AI Models
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