Simple icons are very popular these days, and I’ve created hundreds of them in the last several years. As they are used in a variety of applications, they must be designed and illustrated in manner that allows use at any size. It’s also advantageous to create them as one- or two-color png files with transparent backgrounds for easy use in Powerpoint. The coloration allows the end-user to change the color independently within Powerpoint, and the transparent background vastly increases their usability, allowing them to be used on top of most templates and/or other graphic elements.