Editors and designers choose typefaces for practical reasons as well as for their aesthetic and historical references, and should be aware that their choices will evoke moods, places, times and current or bygone fashions. Editing software makes it possible to use any size of type and removes the need to stick to preset intervals. But, a font, which is a set comprising the alphabet, numbers and punctuation, may be designed to be used only within a narrow range of sizes. Graphic artists and many editors view the type alterations available in software programs, such as outlines, shadows, hollow faces, underlining and so forth, as treatments to avoid. Editors can explore styles and develop an eye for elements to borrow by reading histories of graphic arts. Books on poster art, too, reproduce pieces of genuine beauty and artistic merit, which have become museum pieces and collector's items.