xDai is a stablechain with its own mainnet that operates as a parallel blockchain to that of Ethereum. It was developed through the POA Network, which allows you to make transactions with a low commission on gas (1 Gwei!) and to create a block in just 5 seconds. It uses a Proof Of Authority (PAO).
The birth of this project was made possible thanks to a partnership between POA Network and MakerDAO (which creates Dai that work on the Ethereum network).
The native token is xDai, and is linked to the value of the Dai, Maker's stablecoin, with a 1: 1 rate. Consequently, it too can be thought of and defined as a stablecoin linked 1: 1 to the value of the dollar.
Users can convert their DAI to xDai thanks to the POA network, which acts as a bridge between the Ethereum blockchain and the xDai stablechain.
The Smart Contracts of this protocol offer a certain degree of compatibility with the other EVM (Ethereum Virtual Machine) chains.
The correct performance of the network is supported by a group of validators who implement a consensus process for transactions. Currently the validators are organizations selected by the Ethereum community, which are decentralized autonomous entities, like all those that are part of the crypto world after all.

CASES OF USE
But why use xDai? The cost of transactions is significantly lower than Dai (I can send 500 transactions for 1 cent!) and the network is much faster.
If I have to create a dapp or a site that requires the use of stablecoin ... xDai is definitely the best choice!

CONVERT FROM DAI TO XDAI
With Dai Bridge (POA Network) you can easily convert Dai to xDai. Just connect your Metamask to the site (Ethereum Mainnet). If we have Dai the balance will appear and after 8 confirmations we will have our xDai on the xDai mainnet.
How can I use xDai at this point? The site we used is an exchange that bridges the two mainnets so we will not be able to send our xDai (the conversion took place in our Metamask!).

XDAI METAMASK MAINNET
Obviously we will have to add xDai mainnet to our Metamask (otherwise we will not see our xDai).
-Open Metamask and select “Custom RPC” from the network dropdown
-Select "Custom RPC settings" and enter the xDAI network details below:

Network Name: xDai
New RPC URL: https://rpc.xdaichain.com/
Chain ID: 0x64  (100)
Symbol: xDai
Block Explorer URL: https://blockscout.com/poa/xdai

By doing so we will read the balance of our xDai that we have converted. By connecting to any site or exchange that supports xDai we will have to use this mainnet for payments.