By default, command items are represented by a link. They can also be represented by a button or image. Use the GridViewCommandColumn.ButtonType property to specify how the command column renders its command items.
Command columns can also display custom buttons within command cells or filter. You can create your own buttons, and define custom actions for them. For example, see How to: Create Custom Command Buttons.
This example shows how to create and initialize a command column with custom command buttons at runtime.