Some ships have multiple variants to specialize a ship for a particular role. Innumerable combinations of ship components, customization items, and other personal touches allows each ship owner to purchase and build their own personalized starship. These ships are used by players and NPCs to explore the universe conducting trade, fighting over cargo, or performing many other activities. Some ship designs are variants of a base design, and are said to be in a series. Over one hundred individual designs of ships (also known as starships) exist in the Star Citizen universe.