What is a flattened pdf?

A flattened PDF is a type of PDF file that has had all of its editable form fields, annotations, and layers merged into a single image. This means that once a PDF file has been flattened, the content cannot be edited or manipulated in the same way as a non-flattened PDF.

Flattening a PDF is often done to ensure that the document's appearance remains consistent across different devices and software, as well as to prevent accidental changes to the content. Flattened PDFs are commonly used for sharing documents that need to be displayed accurately but should not be altered by the recipient.

It is important to note that once a PDF file has been flattened, it may not be possible to recover the original editable content. Therefore, it is recommended to keep a backup copy of the non-flattened PDF if you anticipate needing to make changes to the document in the future.