Decentralized distributed applications are among the many blockchain usage decreases, those with the most disrupting potential, at least in the medium term.For an application to be considered a DApp it must meet the following criteria1/The application must be completely open source, it must operate autonomously without an entity that would control the majority of its issued currency. The application can adapt its protocol in response to proposed improvements and commercialize the feedback but all changes must be decided according to the consensus of its users.2/The application data must be stored cryptographically in the public and decentralized register of the blockchain to avoid the weakness of having a central coordination point.3/The application must use a cryptographic currency (the bitcoin or an internal token specific to its system) necessary for access to the application. Miners must be rewarded for their work of validating new insertions in the public register with this currency.4/The application must generate tokens of its currency according to a standard cryptographic standard of its protocol. This standard acts as proof that peer-2-peer nodes contribute to the proper functioning of the application. Bitcoin uses the proof-of-work.Decentralized Dapp applications can be classified according to several criteria. One method is based on having their own blockchain or using the blockchain of another Dapp.According to this criterion, there are three types of Dapps:Type I: Dapp who have their own blockchain. Bitcoin is the most famous example of type I. Litecoin and other alt-corners are of the same type.Type II: Dapps that use the Type I blockchain from another Dapp. They are protocols and have internal tokens for their operation. The Omni Protocol or La’Zooz are examples of type II.Type III: Dapps that use the protocol of a type II. They are also protocols and have internal tokens for their operation. For example, Safe Network (MaidSafe) uses the Omni protocol to publish safecoins that are used to buy distributed file storage.It is interesting to note that a Dapp does not require any legal entities to operate because it is not a business. A DAP establishes the consensus according to two mechanisms: the proof-of-work POW and the proof-of-stake POS.With proof-of-work, changes in a Dapp are made after consulting the amount of cumulative work that each peer-2-peer member provides in its contribution to the operation of the Dapp. Bitcoin, for example, uses a POW.With the proof-of-stake, the changes in a Dapp are done after asking the members to validate the change. The consensus is obtained by a kind of voting system in which the importance of the vote is proportional to the% of underlying currency tokens that the voting member possesses. For example, the vote of a member who controls 10% of the chips published by the Dapp, would have a weight of 10%. The Omni Protocol for example is based on the POS.Both mechanisms can be used in parallel, as is the case with Peercoin or Decred. Such a combination allows a Dapp to operate with less power consumption than the only proof-of-work and also to be more resistant to 51% attacks.There are three mechanisms by which Dapps distribute their tokens: mining, fundraising and development.1/With mining the tokens are distributed by a predetermined algorithm to the connected members which verify the transactions and thus maintain the blockchain of the Dapp. This is the case of Bitcoin.2/With the fundraising, the chips are distributed to those who finance the initial development of the DAPP. This is the case of Mastercoins.3/With development, tokens are produced according to predefined rules and are available only to the developers of the Dapp.The use of these different concepts and smart-contracts related to the possibilities of evolutions and associations between them, make a spectacular field of application of the blockchain technology.