Bitcoin is Anonymous decentralized digital virtual cryptocurrency. Bitcoin formulation with blockchain and cryptography is the biggest invention ever of this century, so it can be called as global currency also.

Bitcoin is Peer to peer currency so no one control it. And to access bitcoin you must have to set up wallet. Wallets is in different form
as Desktop/Software Wallet, Hardware Wallet, Smartphone/App Wallet, Web Wallet.

After then you have to buy bitcoins to store or spend or sell.

(Above mentioned information is explained on Pocket Bitcoin Guide Source : http://bitgold.co.in) You can find more information.