posted 13 years ago
I think jQuery has been so successful for many of the same reasons that I personally like it: it's very powerful yet terse. It's not invasive -- for example, unlike Prototype, it doesn't change the way that the elements or JavaScript itself behaves. The CSS-like syntax of the selectors is easy to learn. It's extensibility (plugins and the like).
But most of all, because it makes areas that have traditionally been cross-browser nightmares easy (Events, DOM, and Ajax, specifically).