The Millennium Falcon was the personal starship of Han Solo for much of his smuggling career, a true 'hot rod' vehicle and one of the most unreliable starships in history. Solo was forced to constantly tinker with the ships inner workings even in flight. Despite the normally durable and dependable character of Corellian ships, the Falcon was an unpredictable high-powered maverick, even in the Rebel fleet. It's main computer had three auxiliary droid brains which frequently gave the ship it's own internal monologue. It's firepower was capable of fighting off Imperial fighter wings and bombing larger ships. And it's Hyperdrive was famously one of the fastest in existence.
Han Solo acquired the Millennium falcon from Lando Calrissian in a high-stakes sabacc game. Some versions of the story note that at the time Lando owned a used starship lot and had specifically bet 'any ship on my lot'. Han cunningly claimed Lando's own heavily souped up custom job of a YT-1300 which had been carelessly left with the other ships. The Falcon itself was a chop job from the start-having been cobbled together from two scrapped ships in a Na Shadda junkyard. SInce it had been pieced back together, more than one previous owner had worked on improving the design to match some vision of perfection. As a result, any given component on the ship was unlikely to be joined to components made by the same manufacturer. Under Han, speed became the ships Raison d'etre. Solo pushed the ship to its limit and beyond, going so far as to equip his ship with specialized devices to streamline it while it was in a tachyonic state.