Bitcoin is a broad term used to describe three different things.
1. The Bitcoin Currency (Tokens / Units of Account)
This is what is referred to when someone asks what is the price of a bitcoin, or how do I buy some bitcoin(s). Bitcoin Wallets are needed to send or receive bitcoin.
Wallet choices can be found here: weusecoins.com/en/getting-started
2. The Blockchain (Accounting Ledger)
The Blockchain is a public ledger that keeps track of all bitcoins in existence and who owns them.
View the Blockchain here: blockchain.info
3. The Bitcoin Network (Transaction processors / Miners)
This is the growing network of computers that verify and process all the transactions on the bitcoin network.
Details about the Bitcoin Network here: blockchain.info/charts
This video can explain more: