It has a primary use case to facilitate testing. So it gives developers more flexibility while they finalize the design of their PolkaDot projects. Notably, the platform’s rules are not as strict as Polkadot.
The design features of Kusama resemble Polkadot. It uses 2 types of blockchains: a main network called a relay chain where the transactions are permanent and a user-generated network called as parachains. A parachain can be customized for any use while the relay chain enhances security.
The main benefit that Kusama offers is to increase the user base and gain traction in the project before launching it officially on Polkadot.