Bitcoin is an innovative transaction network AND a new form of money.
Bitcoin is a P2P technology working without central authority. Transactions and bitcoins creation are collectively handled by the network. Bitcoin is free and open-source. Its design is public, no one owns or controls Bitcoin, and everyone can us it. Thanks to properties of its own, Bitcoin makes promissing usage that cannot be handled by traditional banking systems.
What are nodes and why do we need them ?
Bitcoin is a P2P network, and still we forget how many of these peers are needed to maintain the network at its best efficiency.
Actually, Bitcoin needs more than just miners to maintain the blockchain, it is the mission of the nodes to relay transactions to the miners. More than that, the transactions need to be relayed in a specific order, the nodes work together to define that order.
To be functional at its full potential, Bitcoin nodes must multiply, to host the blockchain and by the way secure the entire network.
Network status between april.2014 and april.2015: almost a year with less than 6000 reachable nodes.