The simple answer is yes, and Google have been able to index PDF files since 2001. However, a question that is often asked is to what extent can they can be crawled by the search engine bots due to them being non-HTML files. The advanced Google bots are not halted by such obstacles, so fortunately the publication of content in PDF format should not hinder your search engine optimisation efforts. Here are some facts that might come in handy regarding how Google handles PDF documents and to what extent they are indexed:
1. Can Google index all types of PDF files?
Fortunately Google can access and index the majority of PDF files but there are a few exceptions. PDF\’s that are encrypted or password protected are inaccessible to the search engines, for example. The rule that Google gives is that if you can copy text from a PDF file and paste it into a standard text document then they should hopefully be able to index it.
2. Can Google index images from PDF files?
Google cannot index images directly from PDF files unless they have a separate HTML page set up for them. Even on standard web pages Google cannot index images accurately unless they are attributed with a relevant and descriptive \’ALT tag\’ – this renders them inaccessible for the search engines when they are contained in PDF documents.
3. Can Google index links in PDF files?
Links in PDF files are treated similarly to standard HTML links. The one exception is that links placed in PDF documents cannot have the \’nofollow\’ attribute attached to them, but they can still pass PageRank and various other authority-relevant ranking signals. Links placed in a PDF file may even be followed by the search engines after the file itself has been crawled and indexed.
4. Can you stop/remove a PDF file from the SERPs?
You can stop a PDF file from being crawled and you can remove an already indexed PDF document from the results pages. The solution to both is to use the following command in the https header where the file is being served: X-Robots-Tag:noindex This will stop the PDF file being accessed by the search engines; therefore it will not appear in the results pages. If the file has already been indexed then the above command can still be used and the PDF will drop out of the listings over time.
5. Is it classed as duplicate content if copies exist of pages in both HTML and PDF formats?
Google has always suggested that only one version of the page is served to the search engines to avoid such issues occurring. If the same content was going to be used on multiple pages in the HTML format then the solution would be to use the \’rel=canonical\’ tag to nominate one version for indexation. The same applies to duplication between HTML and PDF versions of content. The canonical version can be specified in the HTML coding of the webpage or in the https header with the PDF file source. A preferred version for indexation can also be made by including the URL address in the Sitemap.
6. Will PDF Files rank highly in the search engine results pages?
PDF files can rank highly in the SERPs. The optimisation process for a PDF file is almost like scaling down the process of optimisation for an entire website. Excellent content in a PDF file with a diverse and authoritative link portfolio has as much chance at ranking highly as a well optimised web page (as illustrated by the first image).
7. Can you influence how PDF files are presented in the SERPs?
Google will use two factors to determine how a title for a PDF document is presented in the SERPs. These are the Metadata within the PDF file and the anchor text contained in the links pointing to the file. These will serve as strong indicators to the search engines about how they should title a PDF file when it is being listed. While optimising PDF files might not be the highest priority for everyone\’s SEO strategy, I believe it is well worth knowing how content in PDF files is treated by the search engines. The PDF format is great for presenting long documents in a readable way and should be considered a valuable resource for company\’s who produce guides, instructions or any other type of extended content. If you have any other queries about SEO or link building strategies then please get in touch.
If you rely on PDF files, discuss with our SEO team to see if they\’re properly optimised for Google crawling.
This blog was written over 6 months ago and Internet Marketing and SEO is an always changing industry which means the information within this blog may be out of date. Use caution when using any methods or suggestions within it.
