Parachains are able to lease a slot on Polkadot’s main Relay Chain for up to 96 weeks at a time. Ultimately, Polkadot will offer 100 parachain slots. Further slots will be allocated in batches over the coming months. Not all of these slots will be allocated via parachain slot auctions, as some will be used for governance-enabled common-good parachains, according to a press release.