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.
Halogen bulbs produce a bright white light. They become much, much hotter than other types of bulbs and should not be used near combustible materials or touched during or shortly after use. Fluorescent: These tube-shaped lights are often used as overhead lighting for large areas such as retail stores or home basements.
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.