A tape drive or streamer is a component that is often attached to a computer. It is used to write data to magnetic tape or to read data from it. Usually people use it to do backups. Tape drives are different from hard drives in that the access to the data is sequential (in order). This means to read a certain part of data, all the data before it needs to be read as well. Also tape drives are slow, compared to hard drives. Current capacities range from tens of gigabytes to almost a terabyte, per cartridge.