I have some income that wasn't reported on my W-2 (nor was it taxed while it was earned) that isn't a "tip." How do I report this income?

If you earned the income (not on a W-2), the IRS considers that income self-employment income, and you should enter the income and expenses (if you have them) so that they appear on Form 1040, Schedule C. See the FAQ below. 

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