What is a W9 form

What is a W9 form and what should you do with it?  If you have worked for a company or person who issued you a tax statement at the end of the year please read this before you do anything!

If you provide a product or service, or sell a product or service and you receive payment for it you should receive a document to be used for tax purposes.  I am not a tax professional and you should probably consult with one before submitting your IRS requirements for sure.

But if you want to know what is a W( form then