Given a jQuery object that represents a set of DOM elements, the .even() method constructs a new jQuery object from the even elements in that set. Counting starts from zero!
Consider a page with a simple list on it:
<ul>
<li>list item 1</li>
<li>list item 2</li>
<li>list item 3</li>
<li>list item 4</li>
<li>list item 5</li>
</ul>
We can apply this method to the set of list items:
$( "li" ).even().css( "background-color", "red" );
The result of this call is a red background for the first, third & 5th items.