In other words, you can do more than one Internet function at the same time. But that's just for starters. With Netscape Navigator, Internet Explorer and some other modern browsers, you can easily instruct the browser to open a new window, so that the page that's currently open stays on your screen while you open another one. The technical limit to the number you can have open at the same time is based on how much memory your computer has, but the real limit is based on your patience. Things start to slow down when your browser is grabbing texts and images from more than three or four pages at once.
Various browsers handle the new-window command differently.
E-mail programs are usually less accommodating, often keeping you from writing mail in one window while receiving it in the other. But some do this very well. Try yours to see how it does. Likewise, good ftp programs let you log onto separate ftp servers simultaneously. CuteFTP, the most powerful of the Windows ftp utilities, does this better than any other ftp software I've tried.