A more thorough explanation:

In the context of patents, the background of the invention refers to a section in a U.S. patent application or resulting patent that provides information about the field of art to which the invention belongs, summarizes the existing state of the art, and describes the problem that the invention aims to solve.

The background of the invention section typically includes two subsections: "Field of the Invention" and "Description of the Related Art." The former provides a brief overview of the technical field to which the invention belongs, while the latter describes the existing technologies or solutions that have been developed to address the problem that the invention aims to solve.

It's important to note that any references included in the background of the invention section should be relevant to the invention and predate its date of invention. Including a reference that postdates the invention may be interpreted as an admission of prior art.

Let's say that a company has developed a new type of battery that is more efficient and longer-lasting than existing batteries. In the background of the invention section of their patent application, they would describe the field of battery technology, the challenges that current batteries face, and the existing solutions that have been developed to address those challenges. They might also include references to prior patents or scientific articles that are relevant to their invention.