Tungsten halogen
Known simply as halogen bulbs, they burn at a much higher heat than tungsten and the case has to be made from quartz rather than glass to withstand the temperature.
Light: whiter and purer than tungsten.
Available: in low voltage (low-voltage tungsten halogen or LVTH) and mains voltage. For the former, you'll need a transformer, fitted or inbuilt, to keep the wattage down to 12 volts.
Ideal for: uplighters.
Advantages: energy-efficient. With low-voltage bulbs, the design can be slim and compact. The mains-voltage type can be used in conventional fittings without a transformer, but ask your electrician or manufacturer to be sure.
Disadvantage: expensive to replace.
Fluorescent
They're associated with the harsh, buzzing strips of factories and offices, but they're now available in lots of new varieties.
Light: flat (curved and circular tubes are better).
Available in: compact fluorescent tubes and compact fluorescent bulbs (known as compact fluorescent lamps or CFLs) that look like ordinary ones.
Ideal for: mini strip lights in kitchens.
Advantages: energy efficient and economic. Can be used with mains-voltage fittings.
Disadvantages: can't be fitted with dimmers.