A PDF file, or Portable Document Format, is a type of digital document that preserves the formatting of a file regardless of the software, hardware, or operating system used to view it. This makes PDFs ideal for sharing documents like reports, resumes, and eBooks, as they look the same on any device. PDF files can contain text, images, and links, and they support various features such as annotations and forms. They are widely used in business and education because they maintain the integrity of the original document, ensuring that it appears as intended to all users.