An explanation of the alien race called the ancients from the sci-fi channel tv show called Stargate SG-1.
The ancients are a race of people who eventually become so enlightened that they ascended to a higher plane of existence. They inhabited the city of Atlantis and called themselves the Alterans. The first encounter with the ancients is when we meet Oma Desala. She was protecting the Harcisis in Kheb in Season 3, Episode 20, Maternal Instinct.
These ascended ancients are of high intellect and have quite a few special abilities. The premise is that this is caused by them being much further along in the evolutionary line. Most notably is the fact that they become basically energy. They can however choose to appear in any form they like. They often appear to look like humans for ease of communication. That is, when the lower themselves to communicate with lowly humans at all.
They have many varied other abilities as well. They are telekinetic as well as telepathic. They can heal wounds, they can create fire, they can create illusions and they use energy to fight. Their full powers are not actually know.
Even thought the ancients have all these powers they don't represent a large power in the universe simply because they have so many rules that prevent them from interfering with lower life forms and of course as far as we've seen they are the highest life forms in the galaxy. This leads them to only deal with each other and ignore the rest of the universe for the most part. Even when the universe is on the brink of being destroyed they do nothing. There are a few exceptions such as Oma Desala but even they can only do so much without being stopped and punished by the others.
Doctor Daniel Jackson spent some time as an ascended being, although, he was not actually an ancient. For all of season 7 he was an ascended being forced to follow their rules. He didn't enjoy it too well. He always wanted to help people but wasn't allowed to. Eventually he did try to use his powers to help fight Anubis but Oma Desala stopped him and he 'unascended' and woke up naked with no memory.
The Ancients will not even stop the Ori (a race of beings that the ancients helped to ascend but who crave power and worship) from enslaving or annihilating the entire universe. Although the Ancients are powerful and wise they are also arrogant and self-centered. They strictly follow the rules and no exceptions can be made.
