Blockchain is a distributed ledger that can be used for more than just digital assets. Any data (value) transfer is recorded. And this offers up a slew of new options, mainly if we lower the speed and scalability barriers.
Ethereum is a decentralized, expansive blockchain that allows smart contracts. Ether is the platform's cryptocurrency.
Decentralized applications or Dapps are programs that facilitate interaction without the use of foreign entities. Connections that rely on third parties to accomplish the activity include financial transactions and legal discussions. In this aspect, dApps are advantageous since they implement contracts and agreements using solid code and a layer of computers, rather than depending on the expertise and integrity of 3rd parties.
To put it another way, decentralized applications are more advanced versions of traditional apps that provide you with complete control over your transactions. They allow you to interact with a peer without fear of being judged or having Big Brother watching you at all times. These programs, too, do not require any personal data to operate.