[MSN] The Phishing Filter Add-in offers access to the beta version of a new dynamic online service, updated several times an hour to warn you and help protect your personal information.[MSTP 4.6] Use add-in to refer to software that adds functionality to a larger program, such as the Analysis ToolPak in Microsoft Excel. Add-in can also refer to a driver or a user-written program that adds functionality to a larger program, such as a wizard, a builder, or a menu add-in. Use add-on to refer to a hardware device such as an expansion board or external peripheral equipment, such as a CD-ROM player, that is attached to the computer. On menus, the Add-in command is capitalized as shown, not Add-In.