It is useful in situation where you would like to surf the internet in one window and be able to use the other part of the screen for a web mail service or a web app or compare 2 web-pages side by side or leave one Web page open and viewable while you are browsing other websites.

Yes you can definitely toggle between two browser tabs or even 2 browser windows while comparing 2 web pages or achieving different results however I can say Split Browser is definitely more streamlined and does work wonders.

To use Split Browser, you’ll need to have at least two browser tabs open. Once the add-on is installed to your Firefox browser it adds a new option to the Firefox menu called as "Split" as shown below.

To split your browser window into two, you would need to click on "Split Current Tab to" and select the position of the panes i.e. Above, Right, Left or below. By doing this your two tabs are now merged into one, with the screen split between the two of them as shown below.

There is no Limitation to the number of windows you can open inside your window or you can say Split Browser does give you the option of splitting your Firefox window as many times as your systems memory can support.

To download the Add-on click here, also check out the "Best Firefox Extensions" list.