Nielsen Norman Group: “Jakob Nielsen first wrote about how PDF files should never be read online in 1996 — only three years after PDFs were invented. Over 20 years later, our research continues to prove that PDFs are just as problematic for users. Despite the evidence, they’re still used far too often to present content online. PDFs are typically large masses of text and images. The format is intended and optimized for print. It’s inherently inaccessible, unpleasant to read, and cumbersome to navigate online. Neither time nor changes in user behavior have softened our evidence-based stance on this subject. Even 20 years later, PDFs are still unfit for human consumption in the digital space. Do not use PDFs to present digital content that could and should otherwise be a web page. The usability problems that PDF files cause on websites or intranets are plentiful…”