Superman’s home planet of Krypton was wiped out by terrifying natural/unnatural instability that its leadership decried as fake news (input suitable real-world reference) and aside from hubris, Kryptonians also share a humanlike appearance.
But unlike humans, they are an ancient powerful and highly advanced species. They possess technology thousands of years ahead of anything the inhabitants of Earth possess. Their technology varies usually in type and one such technology consists of highly advanced crystals.
These crystals can store vast amounts of data and information. Superman’s Fortress of Solitude is a recreation of Krypton’s surface, and also serves as a storehouse for all the knowledge obtained by the Kryptonian race from the 28 known galaxies.
The Kryptonians consider themselves as a superior race and many of them are highly xenophobic, however, some Kryptonians are more considerate of other lifeforms, such as The House of El.
Each Kryptonian family, or what is called a “House,” is represented by a crest or symbol, often worn by the head of the house. The House of El, for example, is represented by an “S”-like shape, other houses include The House of Zod and the House of Em.
Their home planet revolves around a star that is far weaker than our sun so their powers aren’t fully realized at home. But by absorbing the sunlight on Earth, a Kryptonian can have almost divine powers.
“Kryptonians are basically humans in their structure and appearance, but their biology is far more advanced than that of Earth-based humans where they are able to utilize energy in their body with far more direct and elaborate manners than Earth-based humans do. The source of their immense energy metabolizing abilities lies in their cells which are said to be the greatest organic power storage units in the known galaxy.”
– DC Wiki
Kryptonian society mainly places its values on arts, science, military might, and theology, strictly dividing its citizens into the five respective guilds: The Military Guild, The Science Guild, The Artists Guild, The Religious Guild, and The Labor Guild. All citizens must choose to be part of a guild or it will be chosen for them against their will.
When Krypton was destroyed, it was thought that the entire Kryptonian race was destroyed. This was largely disproven by the survival of Kal-L or Kal-El, who was sent off Krypton to Earth by their fathers right before their source worlds were destroyed.
Some prisoners of the Phantom Zone, such as General Zod, also survived the destruction of Krypton, as well as Argo City, a Kryptonian colony stuck in a pocket dimension where Kara Zor-El was raised.