What Are Parachains?
The Polkadot network has a ‘hub and spoke’ framework that connects all parachains, allowing independent developers of projects to create new networks with the same framework as the main network. Parachains are connected to the mainchain via a central Relay Chain, which allows each parachain to function independently using the same infrastructure without affecting the entirety of the network.
Although each parachain acts as its own entity, it can still leverage the security and scalability of the Polkadot network and does not need to have a network of nodes, as the mainchain supports it. However, parachains do have ‘collator nodes’, which take meticulous care of keeping data and the status of every parachain, picking the best candidates for incoming blocks.
As part of this process, parachains use XCMP, a cross-chain message-passing protocol that allows for messaging between parachains. Since parachains can work independently of the Polkadot network, they can set their transaction fees according to what they deem fit.