Bitcoin Core runs as a full network node and maintains a local copy of the block chain. This data independence improves wallet privacy and security. Unlike some SPV wallets that transmit addresses to peers, Bitcoin Core stores all transactions locally. With local access to the complete set of headers and transactions, Bitcoin Core can use full verification to tell when peers lie about payments.
However, dealing with the block chain comes at a price. An ever-growing data set causes smaller hard drives to fill up quickly. Furthermore, a new wallet can't be used until the full block chain is downloaded and processed, which can take several hours on mid-range equipment.
These problems can be solved by moving and copying Bitcoin Core's data directory. This article describes two approaches that can be used with either a new or existing Bitcoin Core 0.10.0 installation.