A sidechain is a blockchain which is connected to a parent blockchain (the blockchain to which the sidechains are pegged but which is itself not pegged to another parent blockchain is referred to as the mainchain). This is done by pegging their respective coins to one another. A sidechain lets a user have their own blockchain with any consensus rules and characteristics (i.e. transactions per second, blocktime etc.) that they require but it is linked to the Stratis mainchain in such a way that they benefit from any enhancements made on the Stratis mainchain. In the words of Chris Trew, CEO of Stratis Group Ltd:
“Sidechains provide a means to quickly provision, sandbox and deploy a bespoke blockchain tailored to specific enterprise processes. Because Stratis sidechains remain linked to the well-established Stratis mainchain, enterprises can be certain their blockchain implementations will continue to benefit from enhancements made by our core team of highly-experienced developers.”
One significant benefit from sidechains for the Stratis Platform is scalability. Scalability is the problem that as blockchain technology sees greater adoption, it becomes too slow or too large for many applications. A sidechain founder can specify both the block size and block interval, increasing the number of transactions in each block and/or reducing the time between each block. In this way they can tailor the sidechain to their requirements.
Importantly, smart contracts can be built on top of the sidechain, leaving the mainchain free to exchange funds. The significant slowdown of the mainchain due to having smart contracts deploy and execute from the mainchain has been seen in other popular smart contract offering Blockchain as a Service platforms. Stratis’s sidechains will address this problem. This will further make the Stratis Platform an attractive option for smart contract development.
A sidechain creator can choose to make a private sidechain. This would be a permissioned cryptocurrency similar to what is possible with the Stratis DLT. There are a few key differences between a private sidechain and the DLT, which you can read about here.