The page number is also called folio or pagination, and was aso called column title in the past. The term "column" stands for a narrow text body, and the column title is placed above it.

First and foremost, the page number serves as a means of orientation of the reader - but it is also of significant importance for typesetters, printers and bookbinders for production and assembly.

In most cases, the column title is separated from the main body text by a line.

There are 2 kinds of column titles:

 

dead column title
living column title

A dead column title only contains the page number. It is referred to as "dead" because there is no additional statement. Another term for a dead column title is folio.

The living column title, apart from the folio, also includes information such as an additional statement, the name of the author, the chapter title etc.

In encyclopedias, there's also a kind of page header: It features that specific page's first or last word.

The column title's composition should be simple and restrained. It should under no circumstance compete against the main title.

The position is arbitrary, but usually it is placed at the top.

Of course, if it is at the top in one work, it must be in the same position for the entire work.

NOTE!

Unlike the dead column title, the living column title is already part of the type area!