jQuery is a JavaScript library (NOT A FRAMEWORK) created for faster, easier and cross-browser web design.

jQuery is a gracefully, feature-rich JavaScript library that simplifies web animations, DOM manipulation, event handling, etc.

The slim build of jQuery is introduced in the jQuery 3.0 final release that is created to reduce the jQuery size and improve the page load speed.

Slim build is about 6k gzipped bytes smaller than the regular version – 23.6k vs 30k. It excludes ajax, effects, and currently deprecated code.

A study shows that jQuery is used by 74.1% of all the websites (July 2019).