A web browser is a piece of software that allows you to access, view, and interact with the World Wide Web over the internet. The most common web browser is Google Chrome. Windows 10 comes pre-installed with Microsoft Edge, which is what you're most likely to be using at work.
Here are a few common web browsers.
You can tell which web browser you're using by its icon, or by visiting What's My Browser.
By and large, websites will look identical in all web browsers. You may find that certain sites work better in some browsers than others, however.