Sidechains are crucial for enabling scalability and flexibility in blockchain networks. By allowing for transactions and operations to occur on a sidechain, the parent blockchain is less burdened by additional data or resource-intensive tasks. Sidechains allow developers to experiment with different consensus mechanisms, smart contracts, or tokenomics without altering the main chain. For example, Bitcoin's Liquid Network is a sidechain that facilitates faster and more confidential transactions, and it is used for high-speed trading and financial services.