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To join the bitcoin network and start using the currency, all a user has to do is download an application. Since bitcoin is a standard, there are many implementations of the bitcoin client software. There is also a "reference implementation", also known as the Satoshi Client, which is managed by a team of developers and is derived from the original implementation written by Satoshi Nakamoto.
You can download the Satoshi Client from bitcoin.org. Depending on your operating system, it will be called bitcoin-qt or bitcoind.
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 transactions, 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 Client:: Mobile clients, for smartphones such as those based on the Android system can either operate as full clients, light clients or web clients.
The choice of bitcoin client depends on how much control the user wants over their funds. A full client will offer the highest level of control and independence for the user, but in turn put the burden of backups and security on the user. On the other end of the range of choices, a web client is the easiest to setup and use, but the security and control is shared by the user and the owner of the web service, which introduces counterparty risk. If a web wallet service is compromised, as many have been, the users can lose all their funds. Conversely, if a user has a full client without adequate backups, they may lose their funds through a computer mishap.
For the purposes of this book, we will be demonstrating the use of a variety of bitcoin clients, from the reference implementation (the Satoshi client) to web wallets. Some of the examples will require the use of the reference client, which exposes APIs to the wallet, network and transaction services. If you are planning to explore the programmatic interfaces into the bitcoin system, you will need the reference client.
==== Quick Start - Web Wallet
==== Bitcoin-Qt (Satoshi Client)
You can download the Satoshi Client from bitcoin.org. Depending on your operating system, it will be called bitcoin-qt or bitcoind. The reference client implements all aspects of the bitcoin system, including wallets, a transaction verification engine with a full copy of the entire transaciton ledger (blockchain) and a full network node in the peer-to-peer bitcoin network.
Go to http://bitcoin.org/en/choose-your-wallet and select "Bitcoin-Qt" to download the reference client. Depending on your operating system, you will download an executable installer. For Windows, this is either a ZIP archive or an EXE executable. For Mac OS it is DMG disk image. Linux versions include a PPA package for Ubuntu or a TAR.GZ archive.
[[bitcoin-qt-dl-options]]
.Bitcoin-Qt - Download options for different operating systems
For developers, there is also the option to download the full source code, either as a ZIP archive or by cloning the authoritative source repository from Github. Go to https://github.com/bitcoin/bitcoin and select "Download ZIP" from the sidebar. Alternatively, use the git command line to create a local copy of the source code on your system. In the example below, we are cloning the source code from a unix-like command-line, in Linux or Mac OS:
Bitcoin-Qt keeps a full copy of the transaction ledger (blockchain), with every transaction that has ever occured on the bitcoin network since its inception in 2009. This data set is several gigabytes in size (approximately 16GB in late 2013) and is downloaded incrementally over several days. The client will not be able to process transactions or update account balances until the full blockchain dataset is downloaded. During that tim, the client will display "Out of sync" next to the account balances and show "Synchronizing" in th footer.
====
[[bitcoin-qt-firstload]]
.Bitcoin-Qt - The Graphical User Interface, during the blockchain initialization
image::images/bitcoin-qt-firstload.png["bitcoin-qt first run"]
The bitcoin client is not just an interface into the bitcoin network, it also contains complete implementations of a wallet, a miner and a transaction validation engine that can independently validate any transaction. The client can operate as a full node on the network, bringing the power of a bank onto your laptop or smartphone. With the full client you can store keys, create and validate complex transactions and interact with the network at the same level as any other node. You become a bitcoin banker, as much as a bitcoin user.
Andreas M. Antonopoulos
11 years ago
