What are sub?

Virtually all websites are made up of a number of pages, not just one, very long, the home page. Each page is simply a single file (with extension *. Html or *. Htm), which is formed in the same way as the main page (using the template provided above). For example, this service consists of the following pages (see the table of contents): “HTML for the green”, “Header and content”, “Text”, etc. This organization helps the user navigate the contents and prevent unnecessary loading the whole site at once, which lasted probably a very long time.
All pages are usually recorded in the same directory – as separate files – or in different directories (if we somehow classify them by theme). With a sub you can automatically move to the other by clicking the appropriate link (if you put it)