Here is a brief explanation on what is bitshares are and how they are decentralised.
BitShares is an open-source, public, blockchain-based, real-time financial platform. It provides a decentralised asset exchange – similar to NYSE but for cryptocurrencies and without the need to trust a central authority to handle all the funds – that facilitates trading using an international network of computers, in which anyone can take part. BitShares also provides a cryptocurrency token called "BTS", which can be transferred between accounts and is used to collect fees for network operations and as a collateral for loans. The platform was designed by Daniel Larimer, an American programmer and entrepreneur, and launched in July 2014.
Decentralized asset exchange
BitShares allows its users to trade on the built-in fully decentralized exchange (DEX). While traditional cryptocurrency exchanges rely on their own private servers to store, handle and control all the funds, they also have a history of theft (e.g. Mt. Gox), being hacked (e.g. Bitfinex), or closed down (e.g. BTC-e). The idea of a DEX is to have no access to its users' private keys, which are the cryptographic equivalent of a strong password to a regular Internet account, and to operate on a distributed computer network. This way traders remain in full control of their money and the trading platform itself is more resistant to attacks.
