Not only is Firefox less vulnerable to internet attacks, it has security features built in that let you know when a site you have stumbled upon is unsafe. When you navigate to a page that has been deemed unsafe, you may see the following page:
There's also the Instant Web Site ID which lets you know if a website is legitimate before you have made a purchase.
You can customize it
Install it where you like, import your settings from your current browser, change its appearance, customize your icons on your toolbar, add or delete a toolbar, and choose your add-ons. There are add-ons of all shapes and sizes. There are add-ons that make browsing safer (Web of Trust); some that display the weather report on your status bar (Forecastfox); there's even an add-on that allows you to open sites, such as Windows Update, that only load in Internet Explorer, in a Firefox tab (IE Tab.) It's easy to install new add-ons and even easier to delete or disable them.
Click here for a list of Add-ons.
Great list of features
Awesome bar: The Awesome bar makes it easier to enter addresses and offers you a way to search your bookmarks easily. If you only remember part of an address or just need to find a bookmark, just type a keyword in the address bar and Firefox automatically searches your history and your bookmarks and displays the results in a drop down menu.
Session Restore: Firefox will restore your previous session if it experiences an unexpected close. You also have the option of saving your session upon closing the browser so that you can return to it later.
Spell checker: Right-click on words that are underlined in red, and correct the misspelled words.
Tabbed browsing, a Pop-up blocker, a password manager, a download manager, dozens of search engines integrated into the search bar, a fantastic find feature, and so much more.
Click here for a complete list of features or here to download Firefox .