What is it?
An inventor doesn't necessarily have to hire a patent practitioner to help write the application or to help with the examination procedures. He or she may attempt it on their own.

Applications that are sent to the PTO without the help of a patent practitioner are termed pro se applications. With all the complicated details and expense involved in patenting, filing a pro se application is not recommended, unless the inventor really plans to spend the time necessary to learn the in's and out's of patent law.

Individuals who are not recognized patent practitioners are not allowed to help an inventor write their patent application. Only registered patent practitioners may help an inventor write and prosecute their patent application. In addition, registered patent practitioners (even agents) may act as the power of attorney regarding the patent application throughout the entire examination process.

This means that the agent or attorney may sign certain paperwork (however, many documents must still be signed by the actual inventor), authorize withdrawals from the inventor's deposit account, and receive all correspondence concerning the application. Note that the PTO only sends paperwork out to one address per application.

The Specifics
The power of attorney may be granted to a registered patent agent or attorney. As a rule, firms can never be granted the power of attorney, only individuals.

Alternately, in the case of joint inventors filing a patent application together (without the help of a patent practitioner), the power of attorney may be granted to a single inventor (even though they are not a registered patent agent or attorney) in order to cut down on the confusion. That single inventor will be able to sign most of the paperwork alone and will receive all of the correspondence. He or she will have a heavy load of responsibility.

It is always possible for the power of attorney to be revoked if it's not working out. Reciprocally, the acting power of attorney may withdrawal from the responsibility as long as he or she follows the proper procedures and sufficient notice is given.