Krypton was a planet in the Rao system in orbit of a red sun, that was destroyed by a massive implosion.
Krypton has stark white terrain of jagged frozen plateaus, stretching broadly under heavy, dark skies (becoming redder as their sun grew toward becoming supernova), prompting Jor-El to attempt to persuade the immediate evacuation of the entire planet to the council of elders, to avoid perishing in the cataclysm, to no avail.
Kryptonians themselves were portrayed as being a coolly cerebral society, clad in stark white body-suits emblazoned with the standard of each family's house symbol, and treading through halls of antiseptic, white crystal under crystalline arches. The crystalline motif was employed not only in the architecture, but in the landscape and technology as well, suggesting that the entire planet had been adapted and altered by Kryptonian influence. In 1948, Krypton was ultimately destroyed when its red sun began to collapse; the planet was pulled into the sun and steadily crushed, then exploded in the ensuing supernova.
Jor-El's recordings say that Kal-El will pass through six galaxies during his three-year voyage to Earth. This could either mean Krypton is millions of light-years away, well past the Andromeda Galaxy (making it the most remote of its various locations in any Superman story to date), or located in one of the dwarf galaxies closer to the Milky Way in the Local Group. Also, when Krypton was destroyed, fragments from the planet went into outer space, resulting in the creation of a harmful radioactive substance known as kryptonite.
In this version of the story, both Jor-El and Lara preserve some part of their "essence" (in the form of virtual copies of themselves) in the starship that brings their child to Earth. On Clark Kent's eighteenth birthday, a glowing crystal reveals itself in the ship and compels Clark to take it north. He eventually reaches the Arctic, where the crystal constructs the massive crystalline Fortress of Solitude. Inside, an artificially intelligent hologram of Jor-El appears to him and initiates twelve years of Kryptonian education for the youth.