This form records all the business expenses, like meals and entertainment and driving expenses, that you incurred in 2000 that were not reimbursed to you by your employer. They were totally out-of-pocket.
Business-related education expenses also may be included in this form. To determine if your education expenses qualify, see this
And if you are an employee required to maintain a home office, those associated unreimbursed costs will be reported on this form as well.