Publications Office of the EU
Search engine optimisation - Publications Office Web Guide

Search engine optimisation


Search engine optimisation (SEO) is the art and science of ensuring that search engines such as Google, Yahoo and Bing, recommend a website to users as the best solution to their problem.

To bring users to your site via search engines, you have to follow these SEO principles:

  • ensure that the search engines understand who you are and what you offer;
  • convince the search engines that you are the most credible option for their users;
  • make your content deliverable.

Why implement search engine optimisation?

SEO brings you the most valuable traffic (known as organic traffic), which is free. You do not pay for the ranking of the result the user clicks on to visit your site.

How does it work?

  • On the search engine side
    Search engines, such as Google, Yahoo or Bing want to provide the best results when users search for something. They create powerful keyword-based algorithms that understand the question and evaluate the relative merits of the possible answers by reading webpages.
  • On the website side
    A search engine wants to send its users to websites that provide a great user experience. It looks carefully at the quality and quantity of the site’s content, the user-friendliness of its design and its navigation.
    The search engine also identifies explicitly bad content if it is low quality, has no credibility or is outright misleading. stion and evaluate the relative merits of the possible answers by reading webpages.

What should you focus on?

On-page search engine optimisation

  • Technical search Engine optimisation
  • Content optimisation for SEO

Off-page search engine optimisation

Off-page SEO refers to signals sent to search engines from third-party websites. This category of factors mainly includes links to or mentions of your pages on other people’s sites or social media profiles.

  • Inbound links.
    Links to your content from relevant, authoritative sites send a very strong signal to a search engine that the content is popular and worthwhile. People link to content from their websites or social media accounts because they appreciate it. Links indicate that this piece of content, this website and this author are a trusted, authoritative source of information.
  • Social signals.
    Sharing on social platforms.


Off-page search engine optimisation

Search engine crawlers are also looking at sites’ structures, analysing all internal URLs to find the most relevant ones. To speed up this process and to ensure that all important URLs will be found by search engine crawlers, a sitemap file is implemented. This XML-encoded file is located in the site’s root folder and is written following requirements.

The Publications Office Portal has hundreds of URLs to be referenced for its pages and subsites but also a couple of millions for the publications, people, entities and other content exposed for access and reuse. For the Publications Office Portal, the sitemap file is generated via an automatic process which adds new URLs and removes any that have been deleted. This ensures an up-to-date sitemap on a daily to weekly basis.

Due to the number of URLs, the sitemap file consists of a main compressed sitemap index file, which provides a list of the uncompressed sitemap files, which contain a list of the relevant URLs.

The sitemap index file can handle up to 50 000 sitemap files and each sitemap file handles up to 20 000 URL references.

Videos and images are not included in the sitemap scope as they are recognised directly by the search engine crawlers.


The European Commission’s main internal guidelines on SEO can be found here: