DOC is a legacy Microsoft Word document format used before the introduction of Word 2007. It is a binary file format that contains formatted text, images, tables, and other document elements. While largely superseded by the XML-based DOCX format, DOC files are still frequently encountered in archives and older organizational systems. DOC sample files are necessary for testing backward compatibility in document viewers and converters. Developers use them to ensure that modern software can still open, render, and convert old files without data loss. They are also used to test digital forensics tools that need to extract metadata and hidden information from legacy binary formats.