Internet explorer is the baseline, it opens almost every single web page, it's not particularly fast, nor is it super stable. It is also not very strong against hackers and other web threats, providing a portal for spyware, malware and another annoying bits of code.
Safari, Apples attempt to make the ultimate web browser, has quite a few heads up on IE, it's fast, fairly secure, and also opens most web pages. little details though, it's more lacking in. the bookmark system feels clumsy every time i use it, and you have to dig to find out how to save passwords, it's not a handy pop up prompt. safari is a good bet if you want a simple fast, and secure browser with out all the little features.
Mozilla FireFox, originally Netscape, is one of the most popular browsers. it's fast, secure, has a lot of the little features, and his highly customizable with add-ons as varied as new ways to show download progress, new skins, to add-ins that run special scrips on specific pages, and even a 1337 speak translator. FireFox a good bet for anyone, and with a little work can become the perfect browser for everyone.
Opera is a very nice browser, with no real problems, it's quick, has nice features, but isn't so flashy that you get lost trying to figure out which ones to use. opera has a nice "quick search" feature that make searching for information quick and painless and ties with chrome on ease of access. I don't personally use Opera anymore in favor of chrome, but Opera is easily chromes equal and worth a try at least once.
Google chrome is the most recent entry to the browser world, and it made quite splash when google launched it. Chrome has many ideas that were original to it, such as running each tab as a different process so when one tab crashes your other pages are unaffected, and changing the level of control plug-ins have on the computer. chrome has all the features you need standard, and of course has the easiest way to search google. the URL bar in chrome is also your google search bar. if you type some thing like, google chrome in the URL bar, it will pull up a google search for it. if you type in google.com, it'll pull up the google page, this makes for a much cleaner and more efficient web surfing experience, for me anyways. I personally use chrome for most of my surfing, but some websites do not work properly on chrome, such as the watch instantly feature on netflix, so as much as i love chrome, FireFox is still in my start menu.
If you would like to download safari 4, go here
If you would like to download FireFox go here
If you would like to download Opera go here
If you would like to download Chrome go here
if you need any help with these browsers, feel free to commit