As of 2011, the highest capacity tape cartridge can store up to 5 TB of uncompressed data. That would be equivalent to around 250,000 trees, made into paper and printed. Or, if you prefer, equivalent to half of the entire Library of Congress' printed collection of books and papers!
Using a tape drive to digitally record information and store it on a magnetice tape can be substantially less expensive that other options, especially for companies employing large computer systems. It's a great high-capacity medium for backing up important data, and can be used as an archive that endures much longer than paper can! There are autoloaders that can help to streamline the handling of cartridges, and storage racks or cabinets tend to take up only a fraction of the space used by traditional files.