The USPTO assigns a patent application filing date when the patent application is filed. The USPTO also allows inventors to file a provisional patent application with fewer requirements than for a regular patent application. A non-provisional patent application filed within a year of the provisional application can receive the filing date of the provisional patent application, as long as the non-provisional patent application references the provisional application, and has at least one inventor in common with the provisional application.
The provisional patent can be simpler than a non-provisional application, and as a result is much less expensive to prepare and file than a non-provisional application. The provisional application is required only to have a description of the invention, although patent drawings are also required if needed to understand the invention as explained in https://steemit.com/innovation/@fiserman/what-does-it-take-to-become-a-modern-inventor-in-2019 post.
A provisional patent application provides some protection to individual inventors or small businesses, who want to market their invention to larger corporations or investors before spending the money to write and file a non-provisional patent application. If the invention has commercial value, the investors or larger corporations may be willing to fund a non-provisional patent application as part of a technology licensing arrangement. In any event, the inventors can avoid spending money on a patent application until finding someone willing to fund commercial development of the invention.
The inventors should only disclose the invention to others under a non-disclosure agreement (NDA) until a non-provisional application is filed. Public disclosure of the invention prevents the inventors from filing a patent application in many countries outside the US. Although the US allows filing of patent application within one year from when the invention is first disclosed or a product containing the invention is sold, it is still advisable to avoid disclosing the invention even if a patent application is going to be filed only in the US. For example, the non-provisional patent application filing might be delayed beyond one year following the provisional application date, resulting in a loss of patent rights if the invention had been publicly disclosed as you can read from this https://t2conline.com/reasons-why-it-is-essential-for-entrepreneurs-to-be-innovative/ story.
Provisional patents can be filed on-line or by mail. The provisional application fee is $250 for a large business and half as much for a small entity.