Prior Art refers to any evidence that your invention or idea is already known before a patent application is filed. This can include previous patents, publications, products, or any public knowledge that demonstrates the invention is not new. It is crucial in determining the originality of an invention and can affect the patentability of an idea. When assessing a patent application, patent examiners search for prior art to ensure that the claimed invention is novel and non-obvious. If prior art is found that is similar to the invention, it may lead to the rejection of the patent application. Understanding prior art is essential for inventors and businesses to protect their intellectual property effectively.