Globe shaped light bulbs often function like fixtures. Once screwed into a socket, the globe becomes the decorative element. A strip of vanity lights composed of multiple globe-shaped bulbs mounting over the top and on the sides of a mirror is the best example of combining a light source with a decorative function.
Alternately, incandescent globe light bulbs are found in ceiling-suspended pendants where the bulb, seen from below, becomes part of the overall effect.
The number following the "G" indicates the diameter of the bulb in 1/8 inch increments. A G25 bulb, for example, has a 3.75 inch diameter.