Which types of patent applications are not published?

Provisional applications are not published because they are intended to act as a placeholder for an invention while the inventor continues to develop that invention, secure funding, or prepare a nonprovisional application. By their nature, provisional applications are temporary and do not undergo a formal examination process. As a result, they remain confidential and are not made public, giving inventors the benefit of an early filing date without the immediate need for detailed disclosures that come with publication.

In contrast, international applications and nonprovisional applications typically undergo a publication process, where most of these applications are published 18 months after the earliest filing date. This aspect of patent law is designed to promote transparency and allow for public awareness of inventions that are being claimed.

Thus, the unique characteristics of provisional applications regarding their confidentiality and the lack of publication distinguish them clearly from other types of patent applications, affirming that they are the correct answer to the question about which types of patent applications are not published.