KuCoin Shares (KCS) is the native cryptocurrency of the KuCoin exchange, which is a popular platform for trading various digital assets. KCS can be used to pay for trading fees on the exchange, offering users discounts when they use it for transactions. Additionally, holding KCS allows users to earn rewards through the KuCoin bonus program, where a portion of the exchange's trading fees is distributed to KCS holders. This incentivizes users to hold onto their KCS tokens while participating in the KuCoin ecosystem.