The European Commission published ranking guidelines to increase the transparency of online search engine results. The guidelines require companies, such as Google and Microsoft, to identify search engine algorithmic parameters that determine result ranking and to make them available to third party companies. The main purpose of the guidelines is to improve transparency of algorithmic ranking parameters, given that they determine online visibility and are crucial to the success of businesses. The guidelines on ranking transparency are the first of their kind globally and complement the EU Platform-to-Business Regulation (P2B) 2019/1150 that entered into force in July 2020. The guidelines are not legally binding, but they offer guidance to companies and search engines to comply with their obligation enshrined in the EU Regulation 2019/1150 to be transparent on their ranking services.