What are witholdings?

When something is withheld, that means that it is removed from something else. For tax purposes, it generally refers to the taxes that are removed from a person's paycheck. For example, an employee has the following taxes removed from each paycheck: federal income taxes, state income taxes (if applicable), Social Security taxes, and Medicare taxes.

The federal and state income taxes are prepayments of the tax you're expected to owe, so you will claim these payments when file your tax return.

The Social Security and Medicare taxes (usually referred to as FICA) are taxes that get paid towards benefits you may be eligible for in the future. You pay half of these required taxes and the employer pays the other half (Self-employed people pay the entire amount themselves).