strictly speaking, the bitcoin and/or other cryptocurrencies are "tokens" that reward people for using their computer processing power to verify the transactions that are posted on the blockchain. they are the incentive for doing that. (if you've heard of bitcoin "mining", the mining is actually just doing computationally difficult mathematics you verify the transactions are valid - by doing that they ear some bitcoin.
there are lots of uses of blockchain type technology and i think it will be revolutionary, but perhaps not in the way some people think. bitcoin and blockchain was initially attractive largely to criminals and libertarians - criminals because of the anonymity, and libertarians because it's a currency that cannot be debased by a government.
what blockchain allows is certainty among two parties to transact without any central "trust" authority. so this can be used for lots of things - land registry, art provenance etc.
so far, one of the biggest constraints on wider applications of the technology - apart from the fundamental knowledge gap - is making the leap of imagination to apply the technology without the currency (and finding an alternative incentive for participants to supply nodes and verify transactions). the token/currency represents an ever more expensive tax on transactions on the blockchain, and so for an efficient commercial solution that token needs to be removed.
rachel bootsman, bettina warburg and others have some excellent TED talks on blockchain technology, if you want to find out more.
