Introduction
PDF files are used extensively on websites to host documents, catalogues, brochures, research, forms, reports, and other crucial information. There is an ongoing debate about whether they are beneficial for Search Engine Optimization (SEO) and whether search engines and AI systems can comprehend their contents.
PDF files can, indeed, appear in Google Search and be discovered by AI-powered search systems. However, it is essential to take several factors into consideration when publishing them. Understanding the specifics of SEO and learning how to optimize PDF files will allow businesses to make the most of the opportunities they offer.
How Does Google Process PDF Files?
PDF stands for Portable Document Format. As the name implies, the files are designed to preserve the formatting of the document. Unlike HTML, Markdown, or plain text, a PDF file cannot be opened in a text editor and viewed as plain text. Google processes PDF files differently, as it extracts the text and stores it in a format similar to HTML. As a result, search engines can use the same algorithm to index them.
Google can usually extract text from PDF files, including:
• The body of the document;
• Hyperlinks;
• Other elements of text files.
As a result, PDF files can appear in the search results, similar to regular web pages. Search engines are not aware of the difference and will index them accordingly.
Can a PDF File Be Indexed in Google Search?
PDF files can be and are indexed in Google Search. Moreover, they can be included in the AI-powered search results, also known as the AI Overviews. However, a PDF file is not inherently more SEO-friendly than an HTML page. Both have equal value in terms of SEO, as long as the content can be accessed and understood by search engines.
A PDF file might not rank as high as an HTML page because of several factors, including its size and complexity. Very large files or books with thousands of pages can be challenging to process. The more information there is, the harder it will be for search engines to understand the page. This is especially true for multi-purpose PDF files that describe different topics.
When there is a choice between the two, use HTML pages for presenting information online. Reserve PDF files for downloadable documents, such as application forms, reports, and catalogues.
Can PDF Files Compete With HTML Pages?
Both HTML pages and PDF files have unique advantages and disadvantages. A comparison of the two will help determine which options are better for a business’s website.
The choice between HTML and PDF depends on the intended purpose of the file. In general, HTML pages are easier to work with because they are responsive and can be adapted to different screen sizes. They do not require any special software to be opened, unlike PDF files. Moreover, HTML pages can be organized as a website with multiple pages, whereas large PDF files are challenging to navigate.
On the other hand, there are scenarios when a PDF file is more appropriate. They are easier to edit and share. Moreover, they allow for precise formatting that will appear exactly the same on all devices when printed or viewed as an image.
Pros of HTML Pages
• More versatility;
• Easier editing and management;
• Quicker loading on devices with small screens;
• Greater ability to create responsive designs;
• Option to build an entire website structure;
• Simpler navigation and interaction with multiple pages.
Pros of PDF Files
• Precise formatting and presentation;
• Easier editing and sharing;
• Ability to be embedded in web pages;
• Easier to print and read as images;
• Suitable for downloadable documents;
• Ideal for catalogs, brochures, and company reports with complex formatting.
In general, HTML pages are better because they are easier to use. However, there are situations when a PDF file is necessary, such as when the document needs to appear in a certain way.
Common SEO Issues With PDF Files
As helpful as they may be, PDF files are prone to several common SEO issues. In general, they should be dealt with in the same way as regular web pages. They should also be optimized for keywords and should not be blocked from search engines by mistake. Below are the issues that are specific to PDF files.
Unsearchable Text
One of the most common problems with PDF files is that the text is not easily extracted. This happens when the file contains an image of text, which search engines and computers cannot comprehend. Such files cannot be properly indexed and will appear in search results as any other PDF file. However, the search engines will not understand their content.
Text extraction can be achieved through an OCR scan, but it will produce inconsistent results depending on the document. In any case, businesses should not keep text in images of PDF files. Anyone who wants to ensure that a PDF file is readable by search engines should ensure that the text can be copied and pasted from it. One simple way is to attempt to copy the text into any word processor.
Large File Size
PDF files can quickly become large and contain more data than regular web pages. This happens due to the large size of images, complex formatting, and the inclusion of unnecessary documents. At the same time, search engines have limits in terms of the amount of data processed within a single file. These restrictions are regularly updated and should not be tested.
In any case, businesses should optimize the file size as much as possible. Unnecessary elements, such as extra images or documents, should be removed. Large files should be divided into smaller ones, as long as it makes sense. Moreover, the files should be organized in a way that is easy to understand for both humans and search engines. It is better to use several small files than a single large one with thousands of pages.
Mobile Optimization
PDF files are not mobile–friendly because they present a page that has been printed. It can be challenging to read on a small screen and requires zooming in. In contrast, HTML web pages are easily adapted to mobile phones and do not have this problem. In general, mobile optimization is a best practice that all sites should follow.
When the content of a PDF file can be found in another HTML page, it is better to optimize it for mobile phones. If a PDF file is necessary, a link should be added next to it that states that this document is not optimized for mobile phones.
Duplicate PDF Files
If the same document has been uploaded in PDF format on different websites, it will be recognized as two separate web pages by search engines. However, the contents of the files will be the same, which will lead to the duplicate content penalty. This problem is particularly acute for identical PDF files because it is challenging to tell whether they are the same or not at a glance, as opposed to web pages with different design and text.
In this case, businesses should follow best practices for avoiding duplicate content. First, the PDF file should only be available on one website. If that is not possible, the original document should be found, and the other links should be redirected to it. In any case, the documents should include some form of information about their origin and purpose.
Finally, the canonical link element can be used in the HTTP header to indicate the preferred website.
Missing Metadata
Metadata is data about data, which appears in PDF files in the document properties.
While most users do not interact with this information, search engines can use it to organize the content. Therefore, it is essential to provide a brief description of the document. The title field should be filled in with relevant content, and the document should not appear in search results if it does not concern the provided subject.
The metadata can also be used to identify the author, which is helpful when the document has been created by different people or organizations. In any case, the information in the title and the actual contents of the file should correspond.
Password Protection or Crawling Restrictions
For search engines to be able to index a PDF file, it should not be password–protected. At the same time, website owners may want to prevent search engines from accessing it. This is possible with robot.txt files that prevent crawlers from accessing specific URLs. If the PDF file is not available to search engines, it will not appear in search results.
However, if the document is intended to be found by users, it should not have restrictions or passwords. On the other hand, if the file contains confidential information, it should be kept safe with passwords and crawling restrictions.
Should You Publish PDF Files on Your Website?
It depends on the type of content and the target audience. PDF files are useful when it comes to downloadable documents, such as forms, reports, and brochures. Catalogues and menus are also good examples of PDF files that are useful to customers and contain vital information.
Moreover, this format is helpful when the document needs to look the same on all devices and appear in search results. On the other hand, HTML pages are more versatile and better for building a website. In summary, it is possible to provide an example of how each document type can be utilized.
For instance, a restaurant owner will benefit from having a link to a PDF file with the menu because it is challenging to provide a menu in an HTML page. At the same time, if the menu is also available in an HTML format on the website, it will be easier to use on mobile phones. A company that wants to promote its report or product catalogue can utilize a PDF file to make sure it looks the same on all devices and appears in search results. In general, a PDF file should be used for a document that is hard to present in another format.
Managing PDF File Updates and Indexing
HTML pages are easier to update than PDF files. When a business wants to make a few changes to the page, it can be achieved with a few clicks in the content management system. In contrast, an existing PDF file will have to be edited with a converter program or re-created from the ground up. Another issue is that it may be challenging to update a PDF file because of its size or format.
As was mentioned above, search engines will update a PDF file at their discretion, unlike regular HTML pages. Therefore, businesses should not update a PDF file and wait for the search engines to do the same. Fortunately, several best practices can be followed to facilitate this process.
First, it is essential to maintain the original document that can be used to update the file. It should also be possible to update the PDF file, given its current size and complexity. If a new document has to be created to replace the old one, then it will be easier to update it in the future. In any case, it is essential to update the document, as search engines penalize websites that do not update their content.
Finally, when a new document replaces the old one, it should have a new URL so that it can be indexed independently. Moreover, a new set of HTTP caching rules should be established. They will depend on how often the document is updated. The last step is to ensure that the PDF version of the document is not updated automatically if the HTML version is changed often. It will lead to confusion and will affect the performance of the website due to multiple similar URLs.
If a new URL is used, search engines will have to index it again, as it is not familiar to them. However, this procedure may be required if the old document will no longer be used. At the same time, it is important to remember that it does not guarantee that the document will appear in search results. For this to happen, it should have an anchor from another page. In any case, the best way to update a PDF file is to update the original document and keep the URL the same. This can facilitate the update process.
Are PDF Files Useful for AI Search and Generative Engine Optimization?
PDF files can be useful for AI search and generative engine optimization. First, there is no doubt that they are processed by search engines and can appear in search results, as was discussed above. In addition, they contain lengthy texts that can be useful for artificial intelligence. However, as far as generative engine optimization is concerned, a PDF file is not necessarily more advantageous than a regular HTML page.
Both options have their advantages and disadvantages, and only the content of the document can determine its effectiveness in this regard. If the same information can be provided in a simpler format, it will be a better option for a website. On the other hand, there are situations when a PDF file is necessary because it has been formatted to look the same on all devices.
In summary, there are situations when a PDF file is necessary; however, it should not be used for purposes for which it is not intended. In addition, there are several best practices that will help a business to ensure that the document will be useful for both search engines and users.
Should You Convert LLMs.txt Into a PDF?
In most cases, converting llms.txt into PDF is not advisable. The purpose of this file is to provide any large language model (LLM) with access to information in a simple way. Therefore, using another file format is counterintuitive because it will be more difficult to extract data from it. It is obvious that text is much simpler than PDF. As such, creating a txt file or using a simple text-based format such as Markdown is a better option.
While Google can process a PDF file, it is not the best choice for making data available to artificial intelligence models. In summary, the choice of the document format should be based on the task that the file has to fulfill.
Best Practices for PDF SEO
To summarize, the main points discussed in the article can be presented in a list of best practices for PDF SEO.
• Make sure that the text is searchable so that it can be processed by search engines. The best way to avoid this issue is to ensure that a document does not contain images of text.
• Optimize the file size so that it is not too large. Search engines have limits, and they will not process a very large document.
• Ensure that the file contains a comprehensive description of its contents that will help search engines to understand its purpose. Metadata should also be complete.
• Add website links to facilitate the process of finding the document. If possible, make it more accessible by adding an anchor from another webpage.
• All documents should be made available to people with disabilities or impairments. This may require additional software or adjustments to the structure of the file.
• Provide an alternative to a PDF file in the form of an HTML page. If it is available, users will be able to access the document more easily. However, this is only advisable when it is not necessary to use a PDF file.
• Avoid using the same file on different websites so that it does not appear as duplicate content. If it is still required, redirect users and search engines to the primary website that hosts the document.
• Pay special attention to updates in order to ensure that it is not too difficult to update a PDF file. It should be possible to replace old data with new data without having to redesign the file.
• Make sure that the file is not blocked or password-protected if it has to appear in search results. It is also recommended to ensure that confidential documents are kept confidential.
• Finally, choosing the right file format is essential. In most cases, a PDF file should be avoided unless it is necessary to maintain the presentation of the document.
