A 1099 is a tax form similar to a W-2 form except that there are usually no taxes withheld except that sometimes there is State Withholding withheld. It is important that you include your 1099's with your W-2's when filing your taxes.
A person that is self employed will receive a 1099 tax form. It is best, if self employed to save all reciepts for tax purposes. You will receive the 1099 by the end of January.
Many other versions of a free 1099 form also can be issued. A 1099-INT, for example, is used to denote the interest that the taxpayer earned. A 1099-G form denotes things such as tax refunds and credits received. A 1099-R is for distributions from retirement plans, annuities, pensions and the like. In all, there are more than 20 versions of the free 1099 form.