In the traditional technology world, we are used to connecting into a central authority/server like Facebook, Google for our searches, YouTube for videos and Apple Music for our media. These companies take the benefits either by charges or by milking the data we produce. Decentralised applications hope to rock that model.
Instead they incentivise the people who create content and view the content (using smart contracts), and the content is dispersed.
This site lists some of the evolving decentralised applications running on the Ethereum blockchain. (https://www.stateofthedapps.com/)