Most people use just one web browser, but some of us prefer to have two or more. We might need them to see how various web designs look, or because our most-of-the-time browser doesn't work on all web sites. If you are a Mac user in this situation, there is a great $12 tool for you: Choosy.
Choosy works as your "default browser". When you click on a link or a URL in an application such as a mail program or note taker, instead it taking you directly to a browser, Choosy pops up a tiny graphic that lets you choose between all the browsers on your Mac. Click one, and there you go. The configuration for Choosy lets you select which to put under your cursor so you can do a quick click, and the order of the others, and so on.
I have mostly switched to Chrome, but sometimes need to launch Firefox for some sites, so Choosy is really handy. It also allows me to quickly go to Safari to see how a particular site looks there. It's not that I really want to use it all that much, but the only use cost is the extra click from external applications, and the flexibility makes it worth it. There might be something similar for Windows, but I haven't found it and would love to, given that I have similar needs there.