Plus Cover means that the cover of the booklet is printed on a different paper, usually of a heavier weight, than the rest of the pages. This provides a bit more structure to the book and can help keep the books upright if they are in a rack or just give a nicer feel in hand. Also, with cover weight paper, additional finishing options like lamination and spot coating become available.

It is called "Plus Cover" due to how it is described when providing specifications or getting quotes. The number of inside pages is the variable factor because a cover portion is always one sheet (4 pages), so a page count would be described as, for example, "24 pages plus cover" for a total page count of 28 pages. When the cover is printed on a different paper, it is indicated as "Plus Cover" so the printer knows right away there are two different stocks required.