Gold bars are the main premium currency used to buy extra moves and boosters in Candy Crush Saga.
Players can spend gold bars when they run out of moves, need additional lives, want certain boosters, or need help unlocking some progression features. Gold bars can be obtained through purchases and, depending on the version and events available, through in-game rewards and promotional activities.
A common mix-up is calling them coins, gems, or candy coins. Candy Crush Saga does not use those names for its principal premium currency. Boosters are gameplay power-ups, not a currency: examples include Color Bombs, Wrapped Candies, Striped Candies, and Swedish Fish. Gold bars are what can be exchanged for some of those advantages.
The game is free to play, so purchasing gold bars is optional. Players can also earn boosters through events, challenges, daily rewards, and other activities. The exact shop offers and prices may change between updates, but the gold-bar currency remains the standard answer.