Including the file format type in the name (like report_pdf) explicitly shows the file type without relying on hidden extensions. File name extensions (like .pdf, .docx, .jpg) are the primary technical identifiers that operating systems and software use to determine how to open a file. Adding the format type redundantly in the name itself serves as an additional human-readable clue, distinguishing it from relying solely on the extension or looking solely at the document icon.

This practice is common for files shared broadly or accessed on various platforms. For example, including _pdf ensures a document attached to an email clearly indicates its intended read-only format to recipients, regardless of whether their device hides extensions. Similarly, print shops often prefer names like brochure_print_highres_tif to instantly identify crucial specifications embedded within the filename for large batch processing, aiding sorting and preventing accidental format conversion.

The main benefit is enhanced clarity and avoiding mistakes, particularly when extensions are hidden by default or files are moved between different operating systems. However, it adds visual length to filenames and becomes redundant once the file is opened correctly. While generally adopted as a good practice for shared or critical documents for user-friendliness, it's less essential for internal files where users are familiar with standard icons and extensions. The minor redundancy usually outweighs the potential for confusion in collaborative or public contexts.