Operating System:The software that controls the computer's use of its hard-ware resources, such as memory and disk storage space.

Application Software:is a set of computer programs that helps a person carry out a task. Word processing software, for example, helps people create, edit, and print documents. Personal finance software would help keep track of thier money. Video editing software would help with creating and editing home movies that he might take with a digital camera.

Web Browser:usually referred to as a browser, a software program that runs on your computer and helps you access Web pages.

System Software: operating software is classified as this, but not application software. The primary purpose of system software is to help the computer system monitor itself in order to function efficiently.

Anti-Virus Software: A computer program used to scan a computer's memory and disks to identity, isolate, and eliminate viruses. An example that Grandpa would want to take a look at would be Norton Anti-Virus.