The one idea: it predicts what tends to come next
A generative AI model was shown an enormous amount of human writing, books, articles, websites, conversations, and from all of it, it learned the patterns of how language usually fits together. When you type a question, it does not retrieve a stored answer. It predicts, piece by piece, what words most plausibly come next, based on those patterns.
Think of the autocomplete on your phone that suggests the next word, then imagine that idea scaled up almost unimaginably: instead of one word, it can continue for whole paragraphs, and instead of just your texts, it learned from a huge slice of everything people have written. That is the core of it. It is a very, very sophisticated prediction machine for patterns in language.
