If you're running a recent version of Firefox, you might want to have a look at our articles covering Firefox 1.5.
Now, this is one of the best features of Mozilla Firefox. Almost all of my time online I need to have many browsers open at the same time, and honestly, it can get quite messy sometimes. Mozilla Firefox has however added a very helpful function to the browser, called tabbing.
Open your Mozilla Firefox browser, then press "Ctrl-T" at the same time. Your browser will now open a new tab that can be used, in the same browser window.

As you see by pressing "Ctrl-T" I now have 2 tabs in the same browser. :) You can alternate between these by pressing "Ctrl-Tab". If you need more browsing tabs simply press "Ctrl-T" again.
If you want the browser to open multiple sites when you start the browser, this is possible. Go Tools > Options...and you will see this choice in the "General" selection:

As you see the browser here gives you a variety of options, you can 1. use the pages you're currently browsing; 2. Choose startup pages from you bookmarks; 3. use a blank page. As you see in the screenshot, you can also write it the startpages manually, and if there's more than one, divided with a | mark. Use as many pages as you like. :)
There are more ways to control how tabs work as well, if you right-click on a tab, you'll see something like this:

Here you're able to create new tabs, reload the current tab (reload is also available via "Ctrl-R"), reload all tabs, close other tabs and finally close tab (also available via "Ctrl-W").
This is the second in a series of articles about Mozilla Firefox, if you have Mozilla Firefox related topics you'd like to see covered here, let us know. Comments on this article, thumbs up or flames, can be sent to articles@nidelven-it.no. If you need help using Firefox, we recommend using the Firefox forums.
If you're running a recent version of Firefox, you might want to have a look at our articles covering Firefox 1.5.
If you find these articles useful, you might also want to check out the introduction to Thunderbird, introduction to Open Office, Plone or the introduction to Gaim. We're always looking for more translators.