The libbitcoin-blockchain library is a dependency of libbitcoin-node and libbitcoin-server. The library provides transaction and block validation as well as transaction (memory) and block (orphan) pools.
By default the library depends on the libbitcoin-consensus library. This ensures that consensus checks are identical to those implemented by bitcoind. By building using the --without-consensus flag the dependency is avoided and libbitcoin native consensus checks are used instead.