Satoshi’s Bitcoin 0.3 post on BitcoinTalk provides a great ELI5 summary of the network

“Asserting model 0.3 of Bitcoin, the P2P cryptocurrency! Bitcoin is a digital foreign money utilizing cryptography and a distributed community to switch the necessity for a trusted central server. Escape the arbitrary inflation threat of centrally managed currencies! Bitcoin's complete circulation is proscribed to 21 million cash. The cash are progressively launched to the community's nodes based mostly on the CPU energy they contribute, so you will get a share of them by contributing your idle CPU time.”

Satoshi