What is Provisional Patent Application?

In simple words, Provisional Patent Application is a simple application you file in USPTO to protect your invention without the need to complete drafting all aspects of the invention. Assume you already have the invention and you want to present it somewhere like in a conference, you may quickly file a Provisional Patent Application using descriptions, examples, simple drawings... as far as the 'subject matter' is there. This will secure a 'priority date' for your invention and you have one year to file the Nonprovisional Patent Application with the same subject matter. Provisional Patent Application does not require specific format, no claims are needed and it will not be examined by USPTO.