A header is an identifier placed across the top margin of your document that increases usability and makes it look more professional. The header text repeats on each page of your document -- with such information as the document title and date, author's name and page number -- and helps readers pinpoint where they are in a document. Headers vary depending on the writing style used.
Headers in APA
American Psychological Association-style headers use page numbers and a concise title on each page, known as a running head; they do not include your name. Place page numbers flush right, beginning on the title page. Place the title flush left, and use capital letters. On the title page, introduce the header by including the term "Running head" and a colon, like this: Running head: FORMATTING HEADERS IN APA. For subsequent pages, use the title alone: FORMATTING HEADERS IN APA. If the running head exceeds 50 characters, including spacing and punctuation, use a shortened version of the title.
Headers in MLA
Modern Language Association requires headers that include your last name and consecutively numbered pages. Place your name and page number one-half inch from the top of the page and flush with the right margin in the upper right-hand corner to look like this: Jones 1. The page number may be omitted from the first page if an instructor does not require it.