"Itemizing" is listing on the Schedule A of Form 1040 all amounts you paid during the year for certain items such as medical and dental care, state and local income taxes, real estate taxes, home mortgage interest, and gifts to charity.
When you complete your list, you total the amount spent
and compare the total with your standard deduction. The larger of the two deductions,
standard or itemized, will be the deduction to choose, since it will lower the
amount of federal income tax you will owe.