You need a patent:

• If you wish to stop others from copying your invention.
• If you wish to protect yourself from competitors who may copy your invention and then try to patent it themselves.
• If your product is in stores and you are challenged by a competitor who claims they have patent rights of their own.
• If having a unique new product would allow you to set a much higher selling price.
• If it is important to impress potential investors, customers or retailers.
• if you want to stop illegal copies of your products from entering the U.S.
• If you hope to sell your business for a profit. Patent rights are often the most important asset of a successful business.
• If you hope to license your patented product to others.

And, there may be other reasons, in particular cases, for having a patent.

And, there's more! A patent is based on a patent application. Even before a patent application issues as a patent, the pending patent application can also give important benefits. These are as follows.

You need a pending patent application:

• If you wish to discourage competitors from copying your invention. Those competitors may not wish to invest in manufacturing and marketing a competing product, because your pending patent application could issue at any moment as a granted patent. That uncertainty itself thus helps to protect the invention.
• If you wish to protect yourself from competitors who may copy your invention and then try to patent it themselves. Even if the patent application never issues as a patent, it is a permanent record of your prior inventorship. The published patent application, even if it never issues as a patent, might be used as prior art against later applicants.
• If having a unique new product would allow you to set a much higher selling price. Customers and retailers know that “patent pending” means something, and it suggests that your product or service is new and unique. It can be a good selling point in some cases.
• If investors, customers or retailers would be impressed by the invention.
• If you hope to sell your business for a profit. A pending patent application is often the most important asset of a successful business.
• If you hope to license your invention to others; in this case the pending patent application has status both as a potential future patent and as a trade secret having value. An advantage here is that a licensed trade secret does not expire, unlike patent rights which usually expire 17 years after the date of the patent.
• If you have a new product being shown at a trade show or public event, then you definitely can benefit from having a patent application. Without it, any competitor could copy the invention and file their own patent application. Though such copying is not permitted by the patent laws, proving who is the originator and who is the copier can be very expensive and very difficult.