In World of Warships Blitz there are four types of currency available in the game. These are Gold, Silver, Expeience and Free Experience and each has their own use.
Gold
This currency is used to purchase Premium days and Premium Ships.
Silver
This currency is used for repairing warships and purchasing consumables and upgrades such as supplies, equipment, and new ships.
Experience
This currency is used for unlocking the next ship in the tech tree.
Free Experience
This currency is used for unlocking all new ships in the tech tree.