What are PDF files and how does Google treat them?

Google’s indexing of PDFs in search began back in 2001. Over a dozen years of indexing, it can be determined that PDFs are not the best idea as an SEO add-on. However, their presence cannot always be avoided.

PDF files are converted and indexed as HTML. For PDF files containing images of text, Google uses optical character recognition (OCR) technology to convert the text image to text. Images in PDF files are also indexed in image search results.

When there is a page and a PDF file with the same content, Google usually prefers the classic version of the page as the main duplicate version. This will be the version displayed in search results and considered by Google in terms of ranking.

PDF SEO Threats

• Lack of navigation – Most PDFs lack navigation elements, making it difficult to navigate to other content within a page.
• More difficult to track with analytics tools – Most popular trackers only run JavaScript on the web page and do not work in PDF files.
• Unfriendly to mobile devices – PDF files have a consistent appearance across all devices. This means that there is no such thing as a mobile-friendly PDF file.
• Lack of some SEO attributes – PDF files share some attributes with standard pages, but they also lack many elements such as individual link attributes (nofollow, UGC and sponsored).
• Infrequent indexing frequency – PDF files typically change infrequently, so they are indexed less frequently than pages that are updated more frequently, so they tend to get search engine priority.

Ways to optimize PDF files

• Add a unique meta title and meta description – to be added e.g. in Adobe Acrobat Pro via the Properties option
• Create a PDF file name that matches the document – when saving the file it is a good idea not to use a “working” name
• Add alt attributes to images – to be set in the image editing option
• Take care of the header structure for SEO – the PDF should be based on Hx headers just like when creating e.g. a blog article
• Include links in the document – these should be internal links as the PDF cannot contain the nofollow attribute
• Create valuable content – the quality of the content is also taken into account by Google as in the case of standard web pages 

Summary – is it worth your time?

As you can see optimizing a PDF file is possible, but not that profitable.  Make a user-friendly document with properly placed keywords, but don’t focus too much on it. Afterward, take care of other aspects of SEO such as meta titles, descriptions, links and proper use of meta tags.