The IRS understands we have general personal expenses throughout the year. Instead of allowing us to deduct all those expenses, they give taxpayers the ability to take the annual fixed standard deduction. Each year the standard deduction increases to adjust for inflation and changes depending on your filing status (single, married filing jointly (MFJ), head of household, etc.). In 2022 the standard deduction is $12,950 for single taxpayers, $25,900 for MFJ taxpayers, and $19,400 for the head of household taxpayers.
In the event, that a taxpayer has more qualified deductions than their allocated standard deduction they can choose to itemize their deduction. By itemizing your deductions, you are informing the IRS of the qualified deductions you have that will allow for a larger deduction. The most common itemized categories are state and local income or sales tax, real estate tax, vehicle registration fees, mortgage interest, casualty loss, medical expenses in excess of a certain %, and charity contributions.
In most cases, a taxpayer is not forced to use either deduction and has the opportunity to choose one over the other. There are certain circumstances that revoke this option.