A W-4 is a Employee’s Withholding Allowance Certificate, it informs your employer of how much money to withhold from your paycheck for federal income taxes. You enter how many allowances you want on your W4, the allowances determines how much taxes are taken out of your paycheck.  Less allowances has more taxes taken out of each pay check, more allowances has less taxes taken out of each paycheck.

The number of allowances on a W4, does not have to much how many dependents you claim on your tax return.