Why the accounts in futures contracts are adjusted every day?

I was reading information about Futures Market. It mentioned that 'the accounts of the parties in futures contracts are adjusted every day'. My question is why not the accounts are adjusted at the expiry date of the contract. Isn't that you can't touch the money in the account anyway? What's the purpose of adjusting them everyday?


Thank you in advance!!|||Because leverage is high, and it is very easy to quickly lose more than the capital in your account. They want to make sure you don't exceed your margin requirements. fwiw, my broker does constant mark-to-market, and you can get a margin call at any time of the day.