A cruiser is a warship larger than a destroyer originally made to be capital ships during the World War I and II era, but nowadays they are used for a number of roles. They are most commonly used as command ships, but it is hard to give them a specific role, since most ships nowadays, apart from aircraft carriers and amphibious assault ships, have very similar roles and sizes. Some of the cruiser's roles include launching many kinds of missiles, standoff, communications and command, bombardment, escorting other ships, and special operations. However, many modern ships also do this, with the main difference being size, firepower, and their intended use. This is because naval technology today that is capable of competing with other ships and winning, is very limited. The same was true in World War II, when most ships were built around big guns and speed. In both times, ships with different technology are considered obsolete or impractical and are not used much.
Older cruisers were called battlecruisers. They used large cannons like most other ships when they were first used but have evolved to use the same weapons and technology as modern destroyers. Cruisers were first built around 1915 but became popular among navies in the early 1930s and are still used today. Cruisers have changed over time and have evolved from the old, large, coal-driven ships to the modern smaller, stealthier, and more efficient vessels. Cruisers are still used today but are very different from the older ones. After battleships stopped being used during the Cold War years, due to being designed around large guns, which by then were beginning to be considered obsolete, cruisers were left as the most powerful surface combatant ship. (Not counting aircraft carriers.) Like with most ships, they are most likely to become stealthier, more efficient, and have more advanced weapons in the foreseeable future.