They perform some type of action when selected. The OK button is used to accept all the changes you have made in the dialog box. The Cancel button cancels any changes you made in the dialog box. Most dialog boxes have this button. This is the same as pressing the key.
List boxes contain lists of files, styles, colors or other options that can be chosen from.
To select an item from the list simply click on it once with the mouse pointer. You can drag the box to move through the list. These usually come in sets of selections. If you have a list of radio buttons to choose from, you can select only one of the listed options. These options can be turned on or off.