The large Starfleet explorer class of the 2360s, able to separate its saucer and carrying families, best known through the USS Enterprise-D.
The Galaxy-class is a large Starfleet explorer built at the Utopia Planitia Fleet Yards on Mars and introduced in the 2360s. It was designed for long missions of exploration and carried around a thousand people, including the families of its crew. Its saucer section can separate from the stardrive section, letting civilians stay safe while the battle section fights or flees.
The USS Enterprise-D is the most famous ship of the class, but others included the Yamato, the Odyssey and the Venture. The Yamato was destroyed by an Iconian computer virus, and the Odyssey was lost in the first battle with the Jem'Hadar. During the Dominion War, Galaxy-class ships led whole wings of the Federation fleet and became vital front-line warships.
The class defined the look and spirit of Star Trek: The Next Generation, balancing comfort and exploration with strength. Its role shifted from peaceful flagship to warship as the century went on, and the restored Enterprise-D returned in Picard to fight once more.