Bitcoin wallets hold a user's keys, allowing them to sign transactions on the Bitcoin blockchain. Wallets also allow users to receive bitcoin and store it securely.
Blockchain is the technology that underpins Bitcoin and allows its users to exchange value without a central intermediary. A blockchain is a database containing the entire history of Bitcoin transactions.
A transaction is a transfer of Bitcoin value on the blockchain. Bitcoin transactions are irreversible once added to the blockchain.
Bitcoin is a peer-to-peer currency that is a network of nodes running Bitcoin software. A node is able to receive and communicate transaction information with other nodes in the Bitcoin network. Bitcoin nodes store and verify the blockchain.