Can you explain tax withholding

A withholding tax takes a set amount of money out of an employee's paycheck and pays it to the government. The money taken is a credit against the employee's annual income tax. If too much money is withheld, an employee will receive a tax refund; if not enough is withheld, an employee will have an additional tax bill.

https://www.investopedia.com/terms/w/withholdingtax.asp#:~:text=A%20withholding%20tax%20takes%20a,have%20an%20additional%20tax%20bill.

in some cases a taxpayer can request that withholding be taken out of certain payments like Social Security, pension and IRA distributions, Unemployment compensation payments abd certain others.