Before owning any bitcoin, you need somewhere to store them. That place is called a "wallet." Rather than actually holding your bitcoin, it holds the private key that allows you to access your bitcoin address (which is also your public key). If the wallet software is well designed, it will look as if your bitcoins are actually there, which makes using bitcoin more convenient and intuitive.
Actually, a wallet usually holds several private keys, and many bitcoin investors have several wallets.
Wallets can either live on your computer and/or mobile device, on a physical storage gadget, or even on a piece of paper. Here we'll briefly look at the different types.