In essence because it works properly, and there are a thousand add ons to make it work the way you want it to.
IE still fails to display stuff properly, is still insecure, and crashes easily. Click here
to crash IE.
Shameless C&P from somewhere else:
Depending on whom you ask, Internet Explorer users make up between 60% and 80% of the market share in browser usage. You might be wondering what all the others are using. A significant proportion of those eschewing Internet Explorer have adopted Firefox, the most popular browser by the Mozilla project. But why?
Firefox has a lot of benefits to appeal to browser users of all levels. Firstly, if you're still using IE 6, you won't yet have experienced the magic of tabbed browsing. Instead of having to open web pages in new windows, Firefox lets you open them in a new tab within your current browser window. Tabs are displayed in a row across the top of your browser, and you can easily move between them by clicking them or using a keyboard shortcut (Ctrl+Tab in Windows). You can open a link in a new tab by right-clicking and selecting "Open Link in New Tab", by clicking the link with your middle mouse button or scroll wheel (sometimes you'll need to reconfigure your mouse drive to fix this), or by holding Ctrl and clicking the link.
For a long time, this was the main selling point of Firefox (even though Opera, Safari and other browsers except for Internet Explorer have had this feature for years). However, if you're using Internet Explorer 7, which has finally caught up and now offers tabbed browsing, you may be wondering what further benefits Firefox offers.
Internet Explorer 7 may offer tabbed browsing, but Firefox does it so much better. You can customise the way that tabs behave very easily, and if you close a tab by accident, in the History menu is an indispensable feature which allows you to re-open recently closed tabs – it even opens them in the same position as before you closed it.
That's not all there is to it, though. I've always thought it was a crying shame that tabbed browsing was touted as the most exciting feature of Firefox, because there are so many other fantastic capabilities which tended to go unnoticed, I suppose because of the sheer usefulness of tabbed browsing.
A major plus is increased security. Firefox really looks after you on the web. It won't run any scripts or download any files at all without asking you first, so you can feel safe browsing unknown sites with it. Its built-in pop-up blocker is of a very high standard. Firefox will also warn you if it thinks you've navigated to a "phishing" site – a site which attempts to defraud visitors by imitating the secure login page of a company like PayPal or a bank. You can also clear your private data very easily from your browser, meaning that if you're using it on a shared computer, you can feel sure that your details aren't retrievable by subsequent users. Firefox updates regularly and automatically, so you can be sure that you have the latest, most secure version.
Other features include inline spell checking; session restore (if Firefox crashes or has to close to install an update, it remembers all the tabs you had open and any text you had typed into forms, and restores these at your command if you ask it to – you can also ask it to automatically restore all your tabs every time you start up Firefox); an integrated search bar with several leading search engines already added, as well as the option to add more of your favourites; live bookmarks to manage and view your RSS feeds; live titles (which show you a live update of the most important information on a page); a great bookmark organisation interface; and excellent accessibility, with dozens of keyboard shortcuts. There are also more technical benefits. Firefox supports many software standards, including PNG
images, DOM and SVG. There are many plug-ins which developers will find particularly useful.
One capability I'm inclined to go on about a bit is Firefox's fantastically useful keyword search feature. Wherever you see a search box on the web – Wikipedia, Internet Movie Database, your own website – you can right-click that box and choose "Add a Keyword for This Search…" Then, just choose a name for your keyword search - "IMDB Search", for example – and a nice, snappy keyword – like "imdb" - and then whenever you want to search the Internet Movie Database, you can just type "imdb" and then your search term into the Firefox address bar, and the search results page will be shown automatically. This saves you bookmarking sites that you always want to search, and there's no need to find and click on the search field.
Also, the intra-page searching function in Firefox is just really good. When you press "Ctrl+F", a slim little toolbar opens at the bottom of the window (easily closed by clicking the cross at one end), with your cursor already in the search box. It searches as you type, highlighting terms as you add more letters, and if the word or phrase isn't on the page, the search box turns red. It automatically starts again at the top of the page once it's reached the bottom. You can also opt to highlight all instances of the term on the page.
But that's not all. Firefox is customisable to an incredibly high degree. You can download all sorts of skins and button sets for Firefox, to make it look like your own. (I prefer a super-compact skin which makes the buttons really small and gives me as much screen space as possible for web page content, but others, including visually impaired users, may well prefer some of the chunkier designs.) Also, there are hundreds (literally) of add-ons
. The nice thing is that Mozilla, being, of course, a big proponent of open source software, encourages the use of add-ons, and even offers reviews of its favourites.
There have been some criticisms of Firefox: it's a bit slower than many other browsers (although its Cocoa-based browser for OS X, Camino, is rather quicker), and some users have reported high memory use, although this is less of a problem in the most recent version. Firefox 2.0 does seem to be faster to load than IE7, though.
Of course, you might try out Firefox and find that you still prefer Internet Explorer, but I find this highly unlikely. Firefox outclasses most other browsers in almost every field, and what's more, it's open source – constantly being improved and updated by passionate and dedicated developers, with a chance of version 3.0 being released as soon as November 2007.