The reasons why jQuery is so Popular library

     I believe you have some experienced that jQuery is a fast and concise JavaScript Library that simplifies HTML document traversing, event handling, animating, and Ajax interactions for rapid web development.

     jQuery makes it easy to play with the DOM, add effects, and execute AJAX requests, but what makes it better than writing your own library, or using one of the other (also excellent) JavaScript libraries out there?  Here are the most reasons that I think make jQuery is the most successful JavaScript Library

1. Cross-browser Compatibility One of the biggest challenges in Ajax/JavaScript programming is cross-browser inconsistencies – it will drive you mad. For example, a design that renders perfectly in Internet Explorer 8 but may not run that well in Mozilla Firefox, or an interface component you’ve spent days handcrafting works beautifully in all major browsers except Opera on Linux.  The jQuery team is aware of the cross-browser issues, and more importantly they understand why these issues occur. They have written this knowledge into the library—so jQuery works around the caveats for you. Most of the code you write will run exactly the same on all the major browsers.
2. Fast & Small The jQuery core library is only about 24KB in size (Minified and Gzipped) so it is very easily to include in your application and very fast as well.
3. Short Learning curve & Good Documentation jQuery is very well documented.  You can find all the jQuery documentation at http://docs.jquery.com/
4. A lot of Plugins By including only a core set of features while providing a framework for extending the library, jQuery team made it easy to create plugins that you can reuse in all your jQuery projects, as well as share with other developers. A lot of people have taken advantage of jQuery’s extensibility, so there are already hundreds of excellent, downloadable plugins available from the jQuery plugin repository, with new ones added all the time.
5. jQuery UI jQuery User Interface (jQuery UI ) separates out higher-level constructs and is packaged into a neat library that sits on top of jQuery. Accordions, sliders, dialog boxes, date pickers, and more—all ready to be used right now! You could spend a bunch of time creating them yourself in jQuery but the jQuery UI controls are configurable and sophisticated enough that your time would be better spent elsewhere.