Krypton was a planet deep in space.
It's the homeworld of Kryptonians such as Jor-El, Lara, Kal-El (aka Superman), the Kandorians, Zycree, Logar, Hul and Romlok.
Before Krypton exploded years ago, Jor-El was able to place his infant son Kal-El in a starcraft, sending it to Earth, thus leaving Superman an orphan.
Major Cities
Kandor was once a city located on the planet Krypton. But the evil villain Brainiac reduced the city and it's inhabitants to a tiny size, and placed the city in a bottle. He apparently removed the city from Krypton before it exploded.