This property indicates which image will be shown in front of the caption of the button.
The icon property determines the icon that will be shown in front of the caption of the button. There are three options: no icon, a glyph icon or a (bitmap) image. Glyph icons come from the Bootstrap Halflings collection. The advantages of a glyph icon over a bitmap image are that glyphs are scalable, look sharp on high-resolution screens and their color can be changed by changing the font color. The advantage of an image icon is that it can have multiple colors.