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.
An LED light bulb is a solid-state lighting (SSL) device that fits in standard screw-in connections but uses LEDs (light-emitting diodes) to produce light. 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.