What is Tezos?

Tezos is a peer-to-peer, distributed, unauthorized network that seeks to improve on previous blockchain protocols such as Bitcoin and Ethereum.

One of its features is its on-chain governance which promises a self-modifying blockchain - the protocol can evolve by updating its code after token holders have approved the changes.
In July 2017, the project had a two-week ICO raising around  232 $ million in cryptocurrencies and setting a record high over that period. 

There are 3 key levels in Tezos: network level, transaction level and consensus level. The components are modular, which makes updating easy by swapping the modules. Other networks, such as Bitcoin and Ethereum, can be represented within Tezos by implementing an appropriate interface at the network level.
 

Main features of Tezos

Auto-modification: Tezos can be updated without the need to fork the blockchain due to its self-modifying function. On-chain governance also means that XTZ owners vote on the direction of the blockchain - this election cycle provides a formal process for any proposed protocol changes.
Liquid Proof-Stake: Tezos uses a proof-of-stake consensus model in which each stakeholder can participate in the validation of transactions on the network and be rewarded accordingly.
Formal verification: Tezos' blockchain facilitates formal verification, a technique that mathematically demonstrates the correctness of the code that regulates transactions. This helps protect Smart Contracts and avoid code errors.
Turing completes Smart Contracts: Tezos provides a platform for the creation of Smart Contracts and decentralized applications (dApps)
 

Token XTZ

XTZ is the native cryptocurrency for the Tezos blockchain. With Tezos, token holders can participate in the validation process by making a security deposit. Users are rewarded for contributing to the network and ensuring its security and stability and can lose their deposit if they exhibit dishonest behavior.

The consensus mechanism is very interesting, the so-called: Liquid ”Proof-of-Stake in which any stakeholder being an active part of the process is rewarded. Transaction fees on the Tezos network are optional and users can send transactions with a zero transaction fee.