what is $() in Jquery?

Hi, jQuery uses "$" as a shortcut for "jQuery" which returns a special Java-Script object, this object contains an array of DOM elements that matches the selector.
So, $("#id") == jQuery("#id") also called Selector($).

Some JavaScript libraries uses $ too (example: prototype). To avoid conflict with those other libraries jQuery provides jQuery.noConflict() function. Calling this function the control of the $ variable goes back to the other library that first implemented it. Doing this to use jQuery you can't do this $('div.someClass') anymore, instead jQuery('div.someClass'). Alternatively can do this: jQuery.noConflict();jQuery.ready(function($) { // use $ for jQuery}//use $ for the other libraryWhen writing plugins to avoid problems with the usage of noConflict you can pass 'jQuery' to a function: function($) {//use $ writing your plugin}(jQuery)