Ever sign up for internet that claimed 20 Mb per second, only to find that your files download at 2.5 MB per second? They aren't lying to you. Look closely and you'll see that those two figures use different units: megabits (Mb) and megabytes (MB). Here's what that means:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^The guys over at Techquickie have made an awesome video that explains it as quickly (har har) as possible, so watch the above video if you're confused (or send it to your mom who keeps asking you why they aren't getting 20 megabyte per second download speeds). They also say you can divide your megabit figure by 10 to get a very rough (read: innacurate) estimate of the measurement in megabytes, but you could always use that high school education and divide by 8 (though that may require a calculator, or plugging it into Google) if you want to know the exact equivalent.