A parachain is a parallel chain that attaches to the main network of a blockchain, operating independently of it, but taking advantage of its multiple benefits.
The main network is known as Relay Chain. Among the main benefits it confers to parachains are decentralization, security and scalability.
Polkadot’s blockchain is the pioneer in the use of this type of technology. And it has already developed an important network of parachains that have put it at the forefront of the market.