:enabled

This will find all the enabled elements in the document.

                        $("input:enabled")

This code will find the enabled input elements not the disabled one.

:disabled

This will find all the disabled elements in the document.

                        $("input:disabled")

This code will find the disabled input elements not the enabled one.

:checked

This will match all the check boxes which are currently checked. The syntax is :

                        $("input:checked")

:selected

This matches the elements or options that are selected in a dropdown or in listbox.

                   $("select option:selected")

This code finds the currently selected options in the dropdown.