I am trying to understand sidechains and how they relate to ethereum but all the articles I read keep saying things like:

A sidechain is a separate blockchain that runs independent of Ethereum and is connected to Ethereum Mainnet by a two-way bridge

That is from here

But I don't get it. Solana has bridges to Ethereum, does that make Solana a side chain of Ethereum? Polkadot has bridges to Ethereum, is that also a side chain?

I mean what makes an ethereum "sidechain" distinct from other "chains" that can also have bridges to Ethereum?

Also in the article above, it is stated that:

Sidechains can have separate block parameters and consensus algorithms, which are often designed for efficient processing of transactions

Okay so sidechains have some edge over mainchain, mainly processing speed. If that is the case, why then does it need to be connected to the mainchain and acts as a sidechain to the main chain?

I ask because it is also stated that the sidechain does not derives it's security from the mainchain. So if it does not derive its security from the ethereum mainchain, why does it then even have to have a "sidechain relationship" with the ethereum mainchain.

Can someone please help explain? Thanks

2 Answers 2


Sidechains and layer 2 Ethereum solutions tackle the problem of helping Ethereum scale

The main difference between sidechains and Ethereum layer 2 solutions is that while layer 2 inherits the security of the main Ethereum network, sidechains rely on their own security.

An Ethereum sidechain is a separate blockchain network that runs in parallel to the Ethereum main chain. Sidechains connect to the main chain via a two-way peg system allowing assets to be exchanged between the chains.

There are two basic types of sidechains, one in which a chain is dependent on the other and another where they are independent.

When one chain is dependent on another chain like Ethereum, it can be considered the child chain of this parent chain. Typically, the child chain doesn’t create its own assets and derives any assets from transfers from the parent chain.

Sidechains reduce the congestion on the main chain, reducing the cost for everyone and increasing the usability and scalability of the Ethereum ecosystem.

Sidechains work by connecting to the main chain through a two-way-peg system or bridge.

Sidechains are based on the Ethereum Virtual Machine (EVM), which is the computation engine for Ethereum, and this compatibility with the Ethereum Virtual Machine means developers don’t need to make any changes when they want to use their application in a sidechain. It’s simply a matter of deploying the same code because they all share the same software layer of Solidity and can be accessed through the same Web3 API

So solana & polkadot are not exactly sidechains of ethereum, they just have bridges to transfer assets b/w each other and are not evm compatible as well.

The sidechain relationship is maintained for scaling purposes only


A sidechain is a separate blockchain that is connected to the main blockchain, also known as the mainchain, through a two-way "bridge." This connection allows for the transfer of assets or data between the sidechain and the mainchain.

The relationship between a sidechain and the mainchain is that the sidechain relies on the mainchain for security. Because the mainchain has a large and decentralized network of validators, it is more secure than a standalone sidechain. The sidechain is able to take advantage of this security by being connected to the mainchain through the bridge.

The main reason for using a sidechain is to allow for experimentation or to scale certain types of transactions without putting too much strain on the mainchain. For example, a sidechain could be used to test out a new consensus algorithm or to process a large number of transactions more efficiently.

In the case of Solana and Polkadot, they are not necessarily sidechains of Ethereum because they are separate blockchains with their own mainchains. However, they may have connections to the Ethereum mainchain through bridges, which allows for the transfer of assets or data between the two networks.

It is important to note that the sidechain does not derive its security directly from the mainchain, but rather relies on the security of the mainchain to ensure the integrity of the sidechain. This is because the sidechain is connected to the mainchain through the bridge, and any malicious activity on the sidechain could potentially affect the mainchain as well. Therefore, it is important for the sidechain to have a strong connection to the mainchain in order to ensure its security.

For more information on sidechains, you may want to check out the following resource: "Sidechains" by Blockgeeks

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