QUESTION: I have made a prototype and ready to sell my product. I already have some buyers who want my product. Do I have to get a patent before I start selling my product?
A patent does not give you the right to sell your product. It only gives you the right to stop someone else who is making, using, or selling something that infringes your patent.
A product can be successfully marketed and sold without a patent. And if you are not concerned about other copying your product, then a patent may not be needed before you sell your product. For example, if you are already developing the next version or generation of your product which is much better than your current product, you may not care if others copy your current product.
Another reason for not patenting your product before selling it is that, for utility patents, it can take years - after you file a patent application - to get an issued patent. If you think that you may only be selling your product for a year or so, and that time is less than the time it takes to get an issued patent, filing for a patent may not be beneficial.
However, if you do sell your product before filing a patent, the act of selling starts a one year time clock within which you have to file a patent application. If you do not file within one year, you will be barred from later filing a patent application.
If you are interested in foreign patents, and do not file your patent application before selling your product, you may not have a grace period for filing your patent application after selling. Therefore, selling your product before filing a patent application may prevent you from obtaining foreign patent rights.