Gold

Gold is a currency used in many games.  

 
It is often thought of as the most basic type of currency.
In Warcraft III Reign of Chaos , if you need to build a ziggurat but have insufficient gold you must acquire 120G by sending your acolytes to mine gold from a haunted gold mine. 
In the game Gunbound a player can make gold in many ways. 
Obviously the player can earn gold by winning but most of the gold earned per match is earned from bonuses. 
Achieving certain goals such as reaching a total of 3000 damage in a match will earn the player more gold on top of that. 
In many RPGs, gold is earned by killing enemies or by collecting items from enemies to sell. The same goes for MMORPG's. 
A form of acquiring a lot of gold in MMO's is called gold farming. This is usually when the player finds an area with enemies that either drop good loot to sell for a lot or finds an area with enemies who drop a lot of gold when they die. 
In the Super Smash Bros., series gold coins are used in certain minigames to unlock more trophies. 
In Super Smash Bros. Melee, if someone runs out of all of their lives in middle of the single player action they can pay a certain amount of gold (depends on the difficulty setting) to gain another continue where they left off with all of the lives back. 
In Resident Evil 4, you could spend your gold coins to buy more weapons from the merchant, upgrade preexisting  weapons, buy first aid sprays, and other items available for sale at certain points in the game. 
In Resident Evil 4, gold is dropped by many enemies or you can acquire gold by selling the merchant items.