A web browser is a software application used to access the World Wide Web. The term 'web browser' can refer to three different types of programs: a surfer, a SPIDER, and a USER. A surfer is a program that allows users to view web pages on the internet. A SPIDER is a program that searches the web for information and stores it in a database. Finally, a USER is a program that interacts with web pages and allows users to input data or commands. All three of these programs are essential components of a web browser.