Is an ace worth 1?

Excuse me, but I'm a bit confused about the value of an ace in certain card games. Could you clarify for me if an ace is indeed worth 1 in all circumstances? I understand that in some contexts, like blackjack, an ace can be worth either 1 or 11, but what about in other games? Is there a general rule that applies across the board, or does it vary depending on the specific game being played? Your insight would be greatly appreciated.