A web browser is a piece of software on your computer that you use to view pages from the internet. If you're reading this, you're using a web browser right now.
There are various different browsers around. The most commonly used was Internet Explorer but now Google Chrome is more commonly used. Microsoft has since brought out a new browser called Edge but there are other browsers too also worth checking out such as Firefox, Opera and Safari which is more commonly used on the Apple Mac, iPhone and iPad.