Gold

Gold is the in-game currency of League of Legends. It is used to buy items that give bonus stats and abilities to your champion. There are some differences in gaining gold between the Classic and Dominion game modes.

In Classic (Summoner's Rift/Twisted Treeline, your champion starts with 475 gold (+20/40 with the mastery). The champion then earns more gold by last hitting minions and killing champions (or assisting). Additionally, the champion receives extra gold from killing Epic Monsters and destroying enemy turrets. The champion passively earns 13 gold per 10 seconds. This value can be increased by gold generating runes, masteries, and/or items. The passive gold gain does not activate until minions spawn (at 1:30).

In Dominion, your champion starts with 1375 gold (+20/40). Passive gold gain is 56 gold per 10 seconds, which can be increased by gold-generating masteries, and/or items, though they are less effective. Minions also grant more gold than in classic, but champion kills and assists grant less. There is no global gold to be gained, but gold can be earned by taking capture points.

Gold from minions and monsters
Gold can be earned by landing the killing blow (last hit) on enemy team minions and neutral monsters.
 * The gold earned from minion kills is dependent on the game time. As the game progresses, each minion is worth more. On Twisted Treeline melee and caster minions gold rewards increase by 1 gold after the 1st wave and 1 gold per 5 minutes after that. Siege minions gold rewards increase by 1 gold every 2-3 minutes.
 * The gold earned from neutral monsters also increases over time depending on when the monsters were spawned. In addition the largest monster in a minor camp will slowly increase gold value to a modest cap after approximately two minutes.
 * Pets such as  or   will grant gold to the champion that killed said pet.
 * will grant 10 gold to the champion that kills it.
 * Certain kinds of monsters called epic monsters give gold globally, providing gold for the entire team regardless of which individual champion landed the killing blow, although the champion that does so will receive an additional 25 gold.

Gold from champion kills and assists
Gold can be earned by killing enemy champions. The gold gain associated with a champion kill is determined by how many kills the slain champion has recently accumulated (champions that have killed many enemies without dying are worth more gold). When a champion is killed, the bounty ranges from 15 to 600 gold.
 * The last hitter always receives 100% of the value of the bounty.
 * An extra 58% of the value of the bounty is put into a gold pool. The pool is split equally among all champions who assist (by damaging or debuffing the slain champion or healing/buffing the champion that made the kill within 10 seconds of the kill). If there are no assists, the pool is lost.
 * An extra 100 gold is earned for getting First Blood.
 * The defensive mastery will increase the gold earned from all kills and assists by 8/16/24 gold for the affected champion, though this effect is halved on the Crystal Scar.

Gold from destroying a turret
Whenever an enemy turret is destroyed, every member of your team receives 150 gold, regardless of their position or state.

Gold from destroying the inhibitors/nexus
Destroying an inhibitor or the nexus will grant the player 50 gold, but the latter is irrelevant, as it also causes the game to end.

Gold from champion abilities
Some champions have abilities that grant them additional gold under certain circumstances.
 * passively grants her 1/2/3/4/5 bonus gold for every enemy unit killed.
 * grants a bonus 4/5/6/7/8 gold if it lands the killing blow to an enemy unit.
 * grants her an extra 25 gold on each champion kill or assist.
 * grants him and his allies 2 bonus gold per kill.
 * grants 10 gold when used when enhanced by the mastery.
 * The Summoner Spell will cause the user to gain gold for each of the promoted minion's kills. In addition, if the promoted minion damages an enemy champion who is slain, the player who used  will be credited with an assist.

Gold from destroying a ward
Destroying a or a  will grant the player 25 gold.

Gold from seizing capture points
In Dominion, you will gain 75 gold for neutralizing a point, and 75 gold for capturing a point, except for the first time capturing any given point, wherein every point captured is worth 100 gold. This number is independant of the number of champions involved in the capture of a point.

Passive gold gain
The gold a champion earns without actively killing units is called passive gold gain. Every champion passively generates gold at a rate of 13 every 10 seconds. This gold gain does not begin until minions spawn at each base (from 1:30 onwards). Passive gold gain can also be the result of runes, summoner masteries, or gold generating items.

Items

 * grants an additional 5 gold every 10 seconds.
 * grants an additional 5 gold every 10 seconds.
 * grants an additional 5 gold every 10 seconds.
 * grants an additional 5 gold every 10 seconds.

Masteries and runes
Max Gold per 10
 * The mastery grants an additional 0.5/1/1.5/2 gold every 10 seconds.
 * Greater Quintessences of Avarice grant an additional 1 gold every 10 seconds
 * Greater Seals of Avarice grant an additional 0.25 gold every 10 seconds.
 * By buying all the gold income items, and using the right masteries and runes, the player can achieve a total of 40.25 gold per 10 seconds on classic and 83.25 per 10 on dominion.

Selling items
Items can be sold back at the shop for 70% of their total cost. Items that generate gold, Doran's, and Prospector's items only return 50% of their original cost.