The main currency of the game and is collected via attacking enemies / bounties / missions / items etc.
A strange person shows up at The Farm every week. He will sell you an Exotic for the right amount of Strange Coins. Abbreviated as SC. The gear on sale will last the whole weekend and will not rotate.
You can earn legendary shards by completing Missions. These are then used to purchase items from the Vanguard Quartermaster at The Farm. You can earn legendary shards through bounties also.