The Modern Language Association established stylistic and documentation guidelines to create consistency among publications, allow clear acknowledgement of borrowed material and design easy-to-read materials with minimal distractions. Papers focusing on language, literature and cultural studies typically use MLA format. Most often, sources found on the Web are more likely to be without page numbers.
Purpose
In MLA format, using borrowed words and ideas requires you to include an in-text citation that gives the author's last name and a page number. As the seventh edition of the "MLA Handbook for Writers of Research Papers" explains, the text must include enough detail that your reader can find the source on the Works Cited page. The page number helps the reader find the specific information you cited within that source, but if no page number is available, just give the information you can to point to the source, such as the author's name.
Format
Web sources in particular may omit page numbers from text. In such cases, MLA format allows you to leave out the page number from the citation. Or, if the source uses paragraph numbers on the page, you would type "par." or a section number preceded by "sec." (without the quotation marks) and the number with no punctuation between. Avoid using the page numbers from a printout of a page since readers may use different hardware or browsers to view the piece. In-text entries for such sources look like these examples:
The followers believed the comet heralded the coming of a savior (Gillette). The followers believed the comet heralded the coming of a savior (Gillette par. 3).