These explain the entire Transformer like a story with diagrams—no code yet, just how data flows, attention works, and why it replaced older models.
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The Illustrated Transformer by Jay Alammar (blog post)
Link: https://jalammar.github.io/illustrated-transformer/
Why: This is the gold-standard easy-to-digest guide. Colorful diagrams show encoders/decoders, self-attention, multi-head attention, positional encodings, and vector flows step-by-step. It's taught at Stanford, MIT, etc., and still the #1 recommendation in 2026 guides. Read it first—it takes 30-60 minutes and demystifies everything. (Bonus: There's a narrated version and an updated book chapter if you love it.) -
Transformers, the tech behind LLMs by 3Blue1Brown (YouTube, 27 min)