What is a provisional patent application??

A provisional patent application is an application for patent which is not examined and cannot issue into a patent. However, a regular non-provisional application can claim its filing date, and perhaps gain priority over later filed applications. A provisional application expires within one year and if the non-provisional is not filed, the rights which it creates expire. The cost of filing a provisional application is lower than the cost for a regular. This is because it does not include a set of claims detailing the proposed coverage of the patent, and carries a lower government filing fee. There are advantages for filing the non-provisional patent application shortly after filing the provisional application, such as expediting examination and allowance of a patent (if approved by the USPTO) and more economy in the procedure overall.

That is a patent application that lasts only 1 year - during that time you should file a utility patent on the invention. It is used for people that want to protect their idea but do not have the money to get a patent until they get funding.