The three primary forms of bitcoin clients are:
Full Client
A full client, or “full node” is a client that stores the entire history of bitcoin trans‐ actions (every transaction by every user, ever), manages the user’s wallets and can initiate transactions directly on the bitcoin network. This is similar to a standalone email server, in that it handles all aspects of the protocol without relying on any other servers or third party services
Light Client
A lightweight client stores the user’s wallet but relies on third-party owned servers for access to the bitcoin transactions and network. The light client does not store a full copy of all transactions and therefore must trust the third party servers for transaction validation. This is similar to a standalone email client that connects to a mail server for access to a mailbox, in that it relies on a third party for interactions with the network
Web Client
Web-clients are accessed through a web browser and store the user’s wallet on a server owned by a third party. This is similar to webmail in that it relies entirely on a third party server
Mobile Bitcoin
Mobile clients for smartphones, such as those based on the Android system, can either operate as full clients, light clients or web clients. Some mobile clients are synchronized with a web or desktop client, providing a multi-platform wallet across multiple devices but with a common source of funds