Historically, the United States Patent and Trademark Office (USPTO) treated patent applications in a confidential manner, where the content did not become public until the patent was issued or until it was referred to in an issued patent.
This all changed in November 2000 when the United States began to publish applications. This change was part of the General Agreement on Tariffs and Trade (GATT), an agreement related to tariffs and trade that was signed into law by former President Bill Clinton in December 1994. As part of the law, the United States joined Europe and Japan, where patent applications are already regularly published. Applications are published electronically on the USPTO's website. This change is one the most significant changes to the US patent system. There are exclusions from the publication requirement, the most significant of which is for applicants who attest upon filing that they have not and will not file an application for the same invention in a foreign country or under a multilateral international agreement, that requires publication of applications 18 months after filing.
A problem that has occurred from this change is that many formulators do not realize that the “patent application” is not a “patent.” Generally, by the time the application publishes, there has been no examination by the US patent office. Therefore, it is impossible to determine what, if anything, will issue from the application. Patent applications have a different numbering system than issued patents. Issued patents have eight digit numbers (i.e. 8,003,087) whereas patent applications have 11 digit numbers (i.e. 20110201836), the first four of which are the year of publication.
The important thing to remember is that applications are not the same as issued patents. Upon examination and a process called prosecution, the claims may be altered, rejected or allowed. The patent application puts on notice that the process has begun.