Many sizes and styles of bulbs can be found at a good electrical supply house, but most fall into one of three categories:
Incandescent. Casts a warm, pleasant light and shows fabrics and paints in their true colors but can make the room uncomfortably warm if too many are used.
Fluorescent. Compact versions that fit standard fixtures cost more than incandescents to buy but use only one-third the electricity. For kitchens, specify warm white (not cool white) tubes for best color rendition.
Tungsten-halogen. This low-voltage incandescent bulb provides an intense beam that's ideal for spotlighting objects. They last longer and use less electricity than standard incandescents but cost more up front and produce lots of heat.