Sidechains

Key points

• Sidechains are independent blockchains connected to a main network, with which they exchange assets through a bridge.
• They have their own rules and their own consensus mechanism, which allows them to offer more speed or specific functions.
• Because they are independent, they rely on their own security, and do not fully inherit the security of the main network they connect to.

What are sidechains?

Sidechains, or side chains, are separate blockchain networks that operate alongside a main network and allow assets to be moved between the two. The idea is to relieve the main network and offer features it does not have, such as greater capacity or specific resources, while maintaining a connection that allows assets to move back and forth.

How it works

The link between the main network and the sidechain is made through a bridge. To use the sidechain, the user locks assets on the main network, and an equivalent amount is released on the side chain. When returning, the process is reversed: the assets are withdrawn from circulation on the sidechain and unlocked on the main network. This mechanism keeps the two sides in correspondence.

The important difference compared to a second layer is security. A sidechain has its own set of validators and its own consensus, so its security depends on itself, not on the main network. This gives design freedom, but it means the side chain can be more or less secure depending on how it is operated.

This autonomy allows sidechains to experiment with different rules, such as faster blocks or features the main network does not support, serving as an environment for specific use cases.

Why it matters

Sidechains were one of the first responses to the blockchain scaling problem, offering extra capacity without overloading the main network. For a company, they can enable faster or cheaper operations, as long as security and bridge risks are carefully assessed.

Limitations

Since a sidechain's security is its own, it can be weaker than that of the main network, and the bridge that connects them is a sensitive point: bridges have already been the target of attacks that resulted in significant losses. Relying on a smaller set of validators also increases the risk of concentration and failures on the side chain. Evaluating who operates the sidechain and how the bridge is protected is an essential part of using it safely before moving significant value.