The goal of decentralized exchanges is to tackle the problem of the single point of failure, to improve transparency (on-chain exchanges) and improve security (users hold the keys to their wallets, not the exchange).

A stage intermediate between centralized and decentralized is semi-decentralized: exchange keeps order books on its server, but not the private keys.

For review, see 
[Decentralized Cryptocurrency Exchanges](https://hackernoon.com/decentralized-cryptocurrency-exchanges-93039613eeb7)
[State of Decentralized Exchanges, 2018](https://media.consensys.net/state-of-decentralized-exchanges-2018-276dad340c79)

Decentralized exchanges promise lower transaction fees compared to the centralized ones since they do not require proprietary infrastructure. However, they will likely require much higher level of user tech savvy; hence centralized exchanges are likely to persist as onramping vehicles, allowing to convert fiat into crypto.

[0x](https://blog.0xproject.com/the-0x-ecosystem-6f2e780567e8) provides a settlement layer that is being used to build decentralized exchanges.

[One early DEX is EtherDelta](https://medium.com/@david.michael/a-quick-review-of-etherdelta-177215d20f65)
[BitShares 2.0](https://bravenewcoin.com/assets/Whitepapers/bitshares-financial-platform.pdf) is also one of the earliest decentralised exchanges. A stable coin BitUSD was also introduced (quick look at the price shows no stability whatsoever???)

Meet the people behind these projects [Youtube - Token Summit II - Understanding Decentralized Exchange](https://www.youtube.com/watch?v=1eluNnM0f9Q&sns=em) dec 2017

### Analysis

[The Cost of Decentralization in 0x and EtherDelta](http://hackingdistributed.com/2017/08/13/cost-of-decent/)