Coin

Coins (also known as Bird Coins) are the main game currency that appears in some games of the Angry Birds series.

Angry Birds Friends
When you start the game for the first time after the release of the Bird Coins, you get a text box telling you about them, and you can also get  440, but only once. You can earn more for free by earning stars in Weekly Tournaments, and completing them. When you complete a Tournament Level, you will get  2 for ,  4 for, and  8 for , if you get all the stars in a level, you will get  14. You can also get from daily rewards. You will get 4 in the first day,  6 in the second day in a row,  10 in the third day in a row,  16 in the fourth day in a row, and  50 in the fifth day in a row. However, streak will be restart every five days if you login every day.

Angry Birds Go!
Coins are used to upgrade your karts and are used to buy a first new kart! You can also spend coins for power-ups until the Sub-Zero update.

Angry Birds
Bird Coins are so far only appears in Angry Birds for Kakao (Korean version of Angry Birds). They used to purchase Power-Ups and Mighty Eagle. You can earn them by getting stars just for 10 coins.