Clip arts are form of graphic arts widely used in power point presentations. They are pre made images used to depict any medium. Clip arts are generally in build in your computer, if not it is always possible to download online.
Various file formats are available; the most commonly used is Bitmap or Vector Graphics. Bitmap describes the rectangular images which are made of multi-coloured or black and white pixels. The later uses geometric modelling, describing an image in series of points, lines, curves and polygons.
You can use clip art to make online greeting cards to wish them during any occasion.