There is common confusion about how search engines treat PDF pages on the site. Some marketers believe that SEO and PDF are incompatible or website cannot be ranked highly with PDF-pages on competitive demands.
Thus to the question if Google can index Adobe PDFs there is a definite answer: Yes, it can. But it actually does not like to. PDF documents do not have the HTML tag structure which informs Google what it is about and helps to rank the content for target keywords. Thus PDF files confuse Google search engine that in turn prefers keywords and text-heavy documents over PDF ones. By the way, it also happens with Adobe Flash. The truth is that search engines can index PDF and even recognize links in PDF-documents. HTML-pages have no priority while ranking.
In narrow and less competitive search PDF documents can actually reach the top of Google.
Structurally, therefore, use of Adobe PDF will lead to the long tail keywords, for more competitive short tail keywords it is necessary to use HTML.
So PDF-format is really not the best one for SEO optimization. Nevertheless PDF is well scanned by search engines and in certain cases it is the most suitable format for solving problems. For example, if you sell equipment, it is more convenient to store instruction booklets in PDF because you can put the file to download to your site. PDF format is also useful for various directories. Files in this format can be opened on most devices and on almost every computer and their content will look the same everywhere. The main reason for poor ranking of PDF pages is that they are not optimized for search.
If you use the content on the pages in PDF-format the pieces of advice below will help you:
1. Use PDF text files
Search engines are able to recognize the text. With the pictures it will be less obvious. So make sure that your PDF file contains plain text, not words in the form of pictures. If the document you want to convert to the target page of the site is scanned use special tools to convert a document to text.
2. Prescribe title
Search engines pay attention to the ‘title’ tag. You can prescribe it in the document properties. Also in the properties you can assign keywords and information about the author. Experts have not yet agreed whether the last of these properties influence on the rankings, but, at least, there will be no negative impact.
3. Set the SEO-friendly URL / file name
Typically the name of the PDF file becomes a part of the URL, so give the document a simple name, which would contain the keywords.
4. Use standard SEO methods
Do not forget about standard SEO methods. Place the internal links to PDF pages to give them credibility. Place links from your PDF page to other relevant pages. Do not forget about keywords, images optimization, and content of high quality.
5. Cut down the size of the file
The large size of the file will load slower, impacting negatively on the users behavior and ranking. Use special features that will reduce the size of PDF.
6. Avoid duplicating content
Availability of HTML and PDF versions of the same content can be useful sometimes, but only if you take action to prevent problems with duplicate content. Remember that you may receive a duplicate, if you re-download PDF, changing the file name and URL.
7. Do not save the file to read in the latest Acrobat version
Save PDF files in the old version of Acrobat because many users may not have the latest version of the Reader. It is unlikely that someone will update the program in order to read your page.
8. Write protection
Otherwise anyone can upload your file to the site and change it at will (including editing your links).
Summarizing it should be said that despite the fact that the search engines do apprehend PDF pages, webmasters still recommend to use HTML where possible. Users are used to them and feel while working with them more comfortable. In addition, it is easier to add to HTML interactive and social functions. So using of PDF on the site is only appropriate in a few cases:
- You have a lot of PDF pages, which users find valuable;
- Your PDF page is difficult to convert into an equivalent and convenient HTML page;
- The site has content meant for print or download (manual, booklet, form to fill out by hand, etc.);
- Cost-benefit ratio does not seem reasonable. For example, you have only a few PDF pages and you do not want to waste time or money converting them to HTML.
Thanks to luna for tips!