Cruiser-weight starships are the standard combat unit encountered away from large naval bases, the "poor bloody infantry" of most fleets. Nimble scouting frigates have neither the punch nor the stamina to stand up to serious combat, and the mighty dreadnoughts are a strategic resource, carefully hoarded and committed to the most critical battles.
Cruisers perform routine independent "show the flag" patrols in settled systems and lead flotillas of frigates in small engagements, such as pirate suppression campaigns. In major fleet engagements, cruiser squadrons support the dreadnought battle line by screening their flanks against enemies attempting to maneuver for a main gun "bow shot" from their vulnerable broadsides.
Alliance cruisers are named after cities of Earth.