"GB" is a unit of measurement for memory and storage purposes. GB is an abbreviation of gigabyte. One gigabyte is equal to 1,024 megabytes. One megabyte is equal to 1,024 kilobytes. A terabyte is the term used for 1,024 gigabytes.
A typical music track consumes 5 megabytes of storage space, meaning 1 GB can typically hold 200 music files. A standard-definition movie is typically 700 MB, whereas a high-definition movie can be over 4 GB in size. Modern-day hard drives can be over 3,072 GB in storage capacity, or 3 terabytes, as of 2015. A typical operating system consumes up to 40 GB of storage space.