How are keyword searches performed? In the directory system?

Keywords. The request must contain one or more keywords that are the main ones for this document. Soon after submitting a request, the search engine will return a list of links to documents in which the specified words were found.
It is important to choose the right keywords, because if they were unsuccessfully selected, the list of document links may be too long.
Searching for information in a directory is reduced to choosing a specific directory, after which the user will be presented with a list of links to the most informative and visited sites.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.