What does flattening a document mean?

Flattening a document refers to the process of converting a multi-layered file, such as a PDF or graphic design, into a single layer. This is often done to preserve the appearance of the document while preventing any further editing of its contents, ensuring that elements like text, images, and graphics remain intact and appear as intended. Flattening is commonly used in graphic design, printing, and document sharing to maintain consistency across different platforms and devices.