The Bitcoin Blockchain is the distributed transaction ledger that records every bitcoin transaction that has ever taken place. The ledger is secured using cryptography. Transactions are bundled together in the form of “blocks” and miners around the world compete to add these blocks to the blockchain. To add a block to the chain they have to do a lot of repetitive calculations of sha256sum hashes. If they succeed to find the right hash they get to add a block of transactions to the chain.
Electrum 2.0 supports a new make_seed command line option that generates a random seed and displays the mnemonic:
Here are answers to some common questions posed by those new to bitcoin.