Headers and Footers are the names given to information repeated at the top and bottom of a series of printed pages. Look at most published books and you’ll find the title name of the book printed at the top of every page, this is a header. In contrast, the page numbers are often printed at the end of each page, this is the footer.
However any information regularly printed at the top of the page is a header, whilst any regularly at the bottom of the page is a footer.
Headers and Footers in manuscripts nearly always contain the same information - title, author, contact details, page numbers, total number of pages.