Website Testing
Here are some of the browsers I might test in. Click the logo to learn more about each, and to download the latest version of your favorite. Who knows - you might see something you like. Go ahead - download one and try it out! Again, I am NOT recommending one over the other - they are simply the tools I use when optimizing my new web designs. (Note: Some versions of I.E came in both 32-bit & 64-bit versions - it’s usually not necessary to test in both.)
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The 5 most popular browsers in use in the U.S. are (in alphabetical order), Chrome (Google), Firefox (Mozilla), Internet Explorer (Microsoft), Opera (Opera Software), and Safari for iOS-only so, of course, they are always used for testing first. You probably didn’t even know there were that many browsers out there, did you? If you consider all the versions that are still in use there are many more. There are even more still but you likely won’t encounter them unless you use an O.S. other than Windows (Linux, Unix, Mac, or BSD, to mention a few).
IMHO you will be happy with the latest version of one of the “Fab 5” mentioned above. There are a few instances where these browsers are not appropriate; some corporate environments may not allow you to install or update these modern browsers in order to maintain compatibility with their internal facilities or for security reasons. Sorry, there’s not much you can do about that, you’ll just have to wait until they catch up. Meanwhile, you will encounter websites that may not render properly in these “older” browsers. Outdated Browsers is a great way to find out which of the Fab 5 Browsers are currently the most popular, and it includes links to download the latest version of each. Check it out.
Are you a Webmaster? Have you checked your designs in at least the “Fab 5” browsers? Do you use a Code Validation app or service? You should, especially if you want your websites to be useful internationally. Rigorous code validation goes a long way toward making sure your designs are consistent across (most) browsers in use today but keep in mind, not all browsers have caught up to the latest standards yet. Fortunately for us, they are not in the Fab 5. Can you guess why? 
If your favorite browser isn’t listed here and you think I should be testing with it, please tell me about it. I’d be happy to hear from you and possibly include it in my testing repertoire.
Note: May 9, 2012. As of Ver. 5.1.7 Apple no longer supports the Safari browser on Windows. (In fact, even on the Mac it has a very low percentage of users.) Depending on your configuration, some file-types may not display properly (or at all) on these machines. If you see a blank page instead of the expected file try a different browser which, given the lack of support from Apple, you probably should do anyway. I’m just sayin’…