Simon Willison’s Weblog

You can think of the attention mechanism as a matchmaking service for words. Each word makes a checklist (called a query vector) describing the characteristics of words it is looking for. Each word also makes a checklist (called a key vector) describing its own characteristics. The network compares each key vector to each query vector (by computing a dot product) to find the words that are the best match. Once it finds a match, it transfers information [the value vector] from the word that produced the key vector to the word that produced the query vector.

— Timothy B Lee and Sean Trott