A blockchain is an open, distributed ledger that records transactions in code. In practice, it’s a little like a checkbook that’s distributed across countless computers around the world. Transactions are recorded in “blocks” that are then linked together on a “chain” of previous cryptocurrency transactions. “Imagine a book where you write down everything you spend money on each day,” says Buchi Okoro, CEO and co-founder of African cryptocurrency exchange Quidax. “Each page is similar to a blo...