What is use tax return?

Many states have a "use tax or "consumer use tax" to collect monies to cover internet purchases for which no sales tax has been collected.  For example, if you order something online from another state, you may not be charged sales tax for your state.  This use tax is to recover that sales tax (or a portion of it) that the state missed out on.  

Many state tax returns include collection of this tax.  You, as the consumer, are expected to keep records of the purchases that qualify so that the state can collect this money.  For most states, this is strictly on the honor system.