Tech 101: What are MB, GB, and TB? - as part of the expert series by GeoBeats. The difference between a kilobyte, which is KB, a megabyte which is MB, a gigabyte which is GB and a terabyte which is TB is size and nothing more. A kilobyte, KB, is a 1000 bytes. Bytes are pieces of information and a file is made up of bytes. A three page word document is approximately 30 kilobytes or 3000 bytes. A megabyte is a 1000 kilobytes. A gigabyte is a 1000 megabytes. And a terabyte is a 1000 gigabytes. Now what does that mean? Not much. The only time this becomes really important is when you are trying to back things up or move them. Your hard drives on today's computers are enormous. You generally see 320 gigabtye or 500 gigabyte or even now, a terabyte of hard drive space. But when you are trying to move those files somewhere else, that is when it becomes important. Again, a three page document has approximately 30 kilobytes. A photograph, taken at high resolution, is anywhere from one to three megabytes. A song, a music file, can be anywhere from two to six or eight megabytes. You rarely see things as big as a gigabyte until you get into video. And then it gets more complicated because depending on something called bit rate, it depends on how big the file will actually be. Gigabytes become important when you are backing up home movies, when you are downloading films from the Internet, but other than that, it is not a super relevant size. And if you are buying a new computer, having a terabyte of computer space only becomes important, again, if you plan to create large libraries of either music or videos. A perfect example of an external hard drive is this one built by Maxtor. This is a couple of years old because this is only a 160 gigabyte external hard drive. But again, these are available now in up to two terabyte of space and this is literally a hard drive from a regular desk top computer that has been encased in a plastic case and a power cord and a USB cable have been added and this plugs in to the outside of your computer and creates another large space for storage. The other drive that is very popular these days are called flash, fum or zip drives, usually flash, and again, they plug in through a USB port on the computer. This particular flash drive is an eight gigabyte flash drive and I do not think they make them bigger than a 16 gigabyte these days but again, this stuff is just getting bigger by the day. I generally recommend that if you have an enormous amount of information or more than will comfortably fit on an 8 megabyte flash drive that you do move into an external hard drive. Again, this is a security thing also. It maintains the integrity of the equipment because you do not want these pieces to fail. If they fail, you will lose your information.