An Internet catalog is an Internet portal presenting catalogs of companies and catalogs of links to websites, which are sorted into a tree of categories and subcategories and usually also allow full-text search. Catalogs of companies are more widespread, which can also be specialized in various ways, eg by field or region. Anyone can usually add content for free, it is also common to register with a media agency, where the catalog editors revise and publish these proposals (maintenance is thus more demanding on human resources). Some catalogs are paid or exceptionally require publication on a linked page. The catalog can provide quality search results precisely because of its unique content and is therefore a web search engine, but with the difference that instead of organic results (content obtained by a robot without registration) it mainly displays registered results. However, existing catalogs contain both own and organic results.
The quality of the catalog is defined by the number of published companies or links and the scope and timeliness of information about these, including the correct classification into categories. Quality catalogs benefit not only Internet users (verified content), but also website creators, who thus obtain the necessary off-page factors (important for SEO).
An Internet portal is a website that is used to search for specific and thematic content or other websites. In the 1990s, when search engines did not yet provide sufficiently relevant results, the first portals were the most visited web servers, such as Seznam.cz. They typically contain a catalog of links, companies and other information and internet services, thus acting as a browser landing page.