The eCommerce Blog - by Allegro Group

In various conversations over recent months, I have noticed that a lot of people don’t understand the difference between general, or horizontal search on the one hand, and specialised, or vertical search on the other. Understanding the differences is crucial to understanding how Google abuses its dominant position, because Google systematically describes a vast “search” market that denies any meaningful differences.


I think of these differences from four perspectives:

  1. Operators (like Google) that offer both general search and vertical search services;
  2. Vertical search providers, including Google Shopping;
  3. Websites and advertisers;
  4. Users and consumers.


Natural vs Vertical: Differences in the way search results are selected for display by Google

  • Whereas horizontal search results are selected on the basis of an algorithm that is applied to the entire Web and primarily designed to provide the most relevant pages, vertical search results are selected from a smaller group of sites, often listed in a database that is separate from the index of the Web from which horizontal search results are selected, and that Google deems capable of fulfilling a consumer need that it infers.
  • Google Shopping’s competitors in the vertical product search market, including Allegro’s Polish ( and Czech ( comparison shopping services, similarly select sites for display from a subset of product provider sites and not from the entire Web.
  • Websites seeking to be found in horizontal search results need only to ensure that they can be indexed by web crawlers, whereas those seeking to be included in vertical search results must gain access to distinct databases or other data infrastructure operated by the vertical search provider.
  • Consumers experience horizontal and vertical search results differently. Horizontal results provide an overview of the most relevant places on the Web – an information experience akin to getting directions, while vertical results are a consumption experience.

Passive vs Active, Unstructured vs Structured: Differences in the way the content of the search results is provided

  • Whereas the content of horizontal search results is actively collected, at intervals, by Google’s crawling and indexing technology, and whereas sites appearing in search results have autonomy with regard to the way they design their pages, sites selected for display in vertical search products typically have contractual relationships with Google and actively provide data to Google via a feed – a permanent connection to Google’s systems. This data must be structured according to criteria determined by Google.
  • This is also the case for Allegro’s comparison shopping sites, which require partners to provide product listings in a structured format, and do not collect the data themselves from the Web.
  • Partners of Google’s vertical search services make a clear internal distinction between the activity of building their web pages with a view to their inclusion in natural search results (Search Engine Optimisation or SEO) and that of sending Google structured data for inclusion in vertical search services.
  • Consumers experience passively provided information drawn from web sites as a view (such as a snippet) on what is actually present on a given page (horizontal search results), while they experience vertical search results as product or service offerings.

Open vs Closed: Differences in the way advertisements and other commercial placements are selected for display

  • Whereas AdWords ads are selected by Google from among all bidders in an open auction to respond to a search query, the product or service providers that Google selects for promotion in a vertical search service are drawn from a restricted pool of partners defined by Google. For example, Google might allow bids for AdWords on the keywords “yellow mac” from fashion retailers (yellow raincoats), electronics retailers (yellow Mac computers), and others, but in the Google Shopping product, bids from only one of these categories will be allowed.
  • Similarly, Allegro’s comparison shopping services organise listings according to product categories.
  • AdWords advertisers have a great deal of freedom to purchase the opportunity to be found according to key words they deem likely to drive traffic to their sites, while vertical search partners are purchasing a sales lead that the vertical search service (e.g. Google Shopping or one of Allegro’s comparison shopping services) is qualifying for them. Google’s role as an intermediary is much more active in vertical search than in AdWords.
  • Consumers experience AdWords as a collection of links that a potentially large group of advertisers hope they will find interesting, whereas they experience vertical search results as product or service offerings that the vertical search provider hopes will interest them.


To people who manage web sites, or are in the vertical search or advertising businesses, these distinctions are very clear. Although there are also clear differences for consumers, Google’s practice of tying its vertical search services to its horizontal search results pages often leads to a blurring of the lines in consumers’ minds. That is why both industry and consumers are actively supporting the Commission’s investigation into its practices.


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