Running head
Also called: header, running header
A short version of the paper's title repeated at the top of every page, together with the page number.
The running head identifies loose pages. APA 7 dropped it for student papers — those need only a page number — but retained it for professional manuscripts, where it is the title shortened to 50 characters or fewer, in capitals, flush left, with the page number flush right.
MLA has no running head as such; it uses a right-aligned header with your surname and the page number. Chicago leaves the choice to the publisher or department.