What is Kusama KSM?

Could you please explain what Kusama KSM is? I've heard of blockchain and cryptocurrencies before, but I'm not entirely familiar with Kusama and its KSM token. Is it a new player in the crypto space? What are its main features and what sets it apart from other blockchain networks? I'm particularly interested in understanding its purpose, its relationship with Polkadot, and any potential use cases or benefits for investors. Thanks in advance for shedding some light on this exciting topic!