A preamble is usually used for formal documents; you wouldn't include one in a text to your best friend. noun-A preliminary statement, especially the introduction to a formal document that serves to explain its purpose. noun-An introductory occurrence or fact; a preliminary.
Screw-in types can be used in place of incandescents in standard lamp sockets. Available in a wide spectrum of colors. Warm white tones best duplicate the color of incandescents. Today's fluorescent bulbs come in a wide selection of sizes and can produce warm tones of light similar to those of incandescents.
LED light bulbs are a more environmentally-friendly alternative to incandescent bulbs. LED bulbs use a semiconductor device that emits visible light when an electric current passes through it. That property is known as elecroluminescence. Compact fluorescent s, the most common alternative to incandescent bulbs, use electricity to excite mercury gas until it emits ultraviolet (UV) light.