Word count represents the number of words in a manuscript. The various Harlequin lines are identified by their word count -- Harlequin having turned every aspect of manufacturing and distribution into an art form, knowing that all books in a certain line will be of a specific length (word count) allows the publisher to have the exact right size shipping container for each line.
Though most publishers accept the computer word count as the manuscript's length, word count was traditionally determined using a less scientific formula. For the purposes of determining a book's length, an average of 250 words per page was multiplied by the number of pages in the manuscript. The 250 words per page assumed a 12 point Courier font (standard typewriter) and one inche margins. If other sizes were used, then an average words-per-page could be determined by testing several pages from the manuscript. The reasoning behind this approach was that white space takes up as much room and actual letters in a printed book.