What is the primary function of a PDF file format?

The primary function of a PDF (Portable Document Format) file is to preserve all document formatting. This means that when a PDF is created, it maintains the appearance of the document exactly as designed, regardless of the software, hardware, or operating system used to view it. This characteristic makes PDFs particularly useful for sharing documents that need to look the same for every user, such as contracts, brochures, or digital forms.

Since the PDF format encapsulates text, images, fonts, and vector graphics in a single file, it ensures that the document remains consistent in layout and style, making it highly reliable for professional and commercial use. This capability allows users to share documents without worrying about compatibility issues that can arise from different word processing programs or mismatched fonts.

The other choices focus on specific features that do not define the overall purpose of the PDF format. While PDF files can include compressed images or even support certain interactive elements, these functionalities are secondary to their primary role of preserving document integrity. Likewise, the PDF format is not intended for audio files, which are better served by formats specifically designed for sound content.