Sol Ring is an uncommon one mana colorless artifact card from Magic: The Gathering. At the time of this noding, it has been printed in thirty-nine sets, with a total of seventy-nine variants. It's a safe bet that there will be more as long as new sets are printed.
It is only fully legal in the Commander format and is restricted in Vintage. In all other official formats it is either banned or not legal. Casually, see Rule 0.
Sol Ring allows a player to play it for one generic mana, then tap it to add two colorless mana as early as the turn it enters the battlefield. This makes it a positive mana rock, an example of mana acceleration. Does any more actually need to be written?
“Lost to time is the artificer’s art of trapping light
from a distant star in a ring of purest gold."