The .val() method is used to get or set the value of form elements such as input, checkbox, radio button, select and textarea.

js:

$(function(){
    $('.old-value').text( $('input').val() ); // get the input value
    $('input').val('changed input value'); // set the input value
    $('.click').click(function() {
        $('.old-value').text( $('input').val() );
    });
});​

html:

<div class="well">
    <span class="click">get value</span>
    <input type="text" value="input value">
    <span class="old-value"></span>
</div>

Other examples with jquery .val():

$('select.foo option:selected').val(); // get the value from a dropdown select
$('select.foo').val(); // get the value from a dropdown select even easier
$('input:checkbox:checked').val(); // get the value from a checked checkbox
$('input:radio[name=bar]:checked').val(); // get the value from a set of radio buttons