They are those that allow the user to navigate through the website or application and use the different options or services that exist in it. They are essential for normal use of the page. For example, identifying the session, controlling traffic and data communication, accessing restricted web parts, and so on.

They are those that allow the user to access the service with some characteristics of general character predefined in his terminal or that the own user defines. For example, the language, the type of browser through which you access the service, and so on.