A W-9 form is a commonly used document in the United States for tax purposes. It is also known as the "Request for Taxpayer Identification Number and Certification." The W-9 form is used to collect information from individuals or entities that are considered independent contractors or freelancers, as well as certain types of businesses. The form includes personal information such as the taxpayer's name, address, and taxpayer identification number (usually a Social Security Number or Employer Identification Number). The purpose of the W-9 form is to provide the necessary information for a payer to report payments made to the taxpayer to the Internal Revenue Service (IRS) and issue appropriate tax documents, such as the 1099-MISC form.