Before Vim 7.0 was released last May, I usually had six or seven xterms or Konsole windows open, each with a single Vim session in which I was editing a single file. This takes up a lot of screen space, and isn’t very efficient. With Vim 7.0, users now have the option of using tabs within Vim. With Vim’s tab features you can consolidate all your sessions into one window and move between files more easily.

Source: Vim tips: Using tabs