The USS Defiant NX 74205 Was a Federation Starship of the 24th century
This ship was a protoype for an anti-Borg weapons system, and as such lacked many of the amenities considered standard on other Starfleet starships.
She was equipped with quantum torpedoes, phaser pulse cannon, ablative hull armor. She was also designed to be easy to fabricate and build, allowing minor bases and backwater worlds to build copies.
The Defiant was a mixed success. Excelling in anti-starship combat, she was too limited in other ways. Many starbases built Defiant class ships to act as military rersponse ships, but relied on heavier multi-role ships to get more complex missions accomplished.
Subsequent starship designs showed the lessons learned by the Defiant class.