The jquery is a simple and quick to use javascript library and provides a
rich set of functionality in just few lines of code.The $ symbol is also set up as
a shortcut for jQuery.If you want the convenience of the $ function for jQuery without colliding with some other use of the global $ function, the jQuery documentation suggests the following idiom:

(function($) {
    // Within this block, $ is a reference to jQuery
    // Neat, and clean
})(jQuery);

Referring elements of document in jquery code.
jQuery(’div.panel’)
    All divs with class=“panel”
jQuery(’p#intro’)
    The paragraph with id=“intro”
jQuery(’div#content a:visible’)
    All visible links inside the div with id=“content”
jQuery(’input[@name=email]‘)
    All input fields with name=“email”
jQuery(’table.orders tr:odd’)
    “odd” numbered rows in a table with class “orders”
jQuery(’a[@href^="http://"]‘)
    All external links (links that start with http://)
jQuery(’p[a]‘)
    All paragraphs that contain one or more links  if (t.val() == title) {
              t.val(”);
              t.removeClass(‘blur’);

$(‘input:text‘).hint();

var title = t.attr(‘title’);
    // only apply logic if the element has the attribute
    if (title) {
      // on blur, set value to title attr if text is blank
      t.blur(function (){
        if (t.val() == ”) {
          t.val(title);
          t.addClass(‘blur’);
        }
      });
      // on focus, set value to blank if current value 
      // matches title attr
      t.focus(function (){
        if (t.val() == title) {
          t.val(”);
          t.removeClass(‘blur’);
        }
      });
t.parents(‘form:first()’).submit(function(){
  if (t.val() == title) {
    t.val(”);
    t.removeClass(‘blur’);
  }
})

$(‘#search, #username, input.hint’).hint(); // etc

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