The GAS coin also known as NEO GAS is a by-product of holding NEO and the users are rewarded GAS per NEO per processed block. To understand what is GAS coin, we need to understand, how NEO ecosystem works.
NEO was started in 2014, as Antshares and was also referred to as China's first blockchain platform. NEO is a smart contract ecosystem whose smart contract is called NEOcontracts and is similar to Ethereum. To drive the NEO platform, it involves two tokens, NEO and GAS which are capped at 100 million tokens each. GAS was designed to control the NEO network.
The NEO token is a representative share of NEO ecosystem and the holders are entitled to voting rights and as well as the right to the dividend in form of GAS coin. The GAS coins are used to control the management rights to the NEO. These right include account reconciliation and any changes to network parameters.
"GAS is the fuel token for the realization of NEO network resource control, with a maximum total limit of 100 million." NEO whitepaper
GAS coins are required by companies and users to run their DApps on the NEO blockchain. There is no particular use of GAS coin except using it for paying fees in the NEO and speculating. The GAS coins which the NEO receives in form of transaction fees are recycled back to the NEO holders with all the newly generated GAS coins.
The system is designed in such a way that circulation of the GAS coin will not be more than NEO until 22 years into the project when both tokens will have 1:1 ratio. With the development of NEO ecosystem and as more transaction happens, it will drive the need for more GAS coins and effectively create demand and increase its prices.
The GAS coin is generated at a rate of 8 GAS per NEO block with the construction of the blockchain which means 8 GAS will be distributed to all 100,000,000 NEO. The GAS generation also depends upon the actual block generation rate. The GAS supply is reduced by 1 token for every 2 million blocks and around 2039, it will reach its total supply of 100 million and production will cease. GAS coins can be further divided in the future, unlike NEO.
The conversion rate of NEO to GAS can be calculated from neotogas.com/
The reward calculation is based on two formula, Theoretical calculation and Actual calculation. Theoretical calculation shows the reward based on NEO whitepaper. In the whitepaper, the GAS reward is based on a 15 seconds block generation rate.
Actual calculation rate is based on the actual block generation rate which varies and depends on the nodes and network and that's why it is lower than the theoretical rate.