Here's all you ever wanted to know about provisional patent applications:

Provisional Patent Application is a part of §111 of US Patent Law. When you are not ready to have a patent attorney process your invention data into an application, but you are pressed by other factors to get some kind of legal footing, then the provisional filing is your option. A provisional application is a simple, inexpensive patent application ($110 for a small entity as of today) that will not be examined. Claim language in a provisional application is NOT required by USPTO, but it is recommended by other offices -a precautionary measure in case of an unforeseen litigation. The greatest advantage in filing a provisional is the right to claim an invention's priority date, and the status of a PATENT PENDING.