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Fundamentals

Transformer

The neural network architecture behind most modern large language models, using a mechanism called self-attention to understand context across long sequences of text.

By Sitebard TeamUpdated June 8, 2026

In plain English

A transformer is the underlying design used by most modern AI language models. It lets the model pay attention to every word in a sentence at once, so it understands meaning and context much better than older approaches.

Technical definition

The transformer is a sequence-to-sequence architecture built on multi-head self-attention and feed-forward layers. Each self-attention head computes scaled dot-product attention over all positions simultaneously, allowing the model to capture long-range dependencies without sequential processing. Positional encodings add order information since the architecture itself is permutation-invariant.

Business use case

Businesses rely on transformer-based models for summarisation, sentiment analysis, customer support automation, code generation, and document understanding. Understanding transformers helps explain why these tools are strong at language and why context window size affects what you can process in one call.

Example

GPT-4, Claude, and Gemini are all transformer-based large language models. When you ask one of them to summarise a document, the transformer architecture allows it to attend to every part of the document at once to produce a coherent answer.

Frequently asked questions

A transformer is a type of neural network architecture introduced in 2017. It uses self-attention to weigh the importance of each word relative to every other word in a sequence, allowing it to understand context at scale far better than earlier models.

Recurrent neural networks processed text word by word and struggled with long sequences. Transformers process the entire sequence in parallel and scale efficiently with more data and compute, which enabled today's large language models.

Not technically. Knowing what they are helps you understand why LLMs excel at language tasks and have context limits, but you do not need to study the math to use AI tools productively.

No. The transformer architecture has been adapted for images (Vision Transformers), audio, protein sequences, and time-series data, making it a general-purpose approach across many AI domains.

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