This amendment granted the United States the right to collect income tax without accounting for the population of the states.
Income Tax Guide
Provided by the Government Printing Office, the above link is a guide to the history of the sixteenth amendment, the purpose, and defines all details of income tax. It is a very good reference guide if one has questions about this amendment.
This cartoon illustrates how costly income tax can be. It encourages individuals to budget their money carefully to be able to pay this tax.