Though job-related tax deductions are most often taken by business owners or taxpayers who are self-employed, you may be eligible for some of these deductions even as an employee of someone else. If your job required that you travel for business purposes during the tax year, or if you conducted a lot of business for your employer from home or out of the office (entertaining clients, for example), you may be able to claim some of the expenses you incurred as a deduction on your taxes -- but only if you were never reimbursed for those expenses by your employer.
As far as the IRS is concerned, an "unreimbursed employee expense" is something you paid for that was required to carry out the job for which your employer hired you. The expense for which you are seeking the deduction must also fall under the IRS's definition of "ordinary and necessary" business expenses, meaning that it is a common part of doing business in your normal line of work. This could include:

Vehicle expenses
Parking fees, tolls, and transportation
Travel expense while away from home overnight
Meals and entertainment expenses

If you plan to claim job-related tax deductions, it is essential to maintain good records of your expenses and exactly what job function they helped with. To claim job-related tax deductions, you must itemize -- and the amount of the unreimbursed business expenses you list must be more than 2% of your AGI.