What is Self-Attention in Transformers and how does it compute contextual representations?
Updated May 16, 2026
Short answer
Self-attention is a mechanism that allows each token in a sequence to dynamically attend to other tokens to build context-aware representations.
Deep explanation
Self-attention is the core innovation behind Transformer architectures and modern LLMs.
Unlike RNNs, which process sequences sequentially, self-attention allows parallel processing while capturing global dependencies.
Core idea: Each token is transformed into three vectors:
- Query (Q)
- Key (K)
- Value (V)
Attention computation: Attention(Q, K, V) = softmax(QK^T / √d) V
Step-by-step process:
- Input embeddings are linearly projected into Q, K, V.
- Similarity scores are computed between queries and keys.
- Scores are scaled and normalized using softmax.
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