Incandescent lamps are cheap but tend to have short lifetimes. The light emitted by incandescent sources is perceived as particularly pleasant because these hot radiators generate a continuous (or full) emission spectrum. Nevertheless, as hot radiators they waste much of the electrical energy supplied to them.
Compact fluorescent lamps (CFLs) are actually among the least compact of all the various lamps commercially available at present. Although CFLs are certainly energy efficient, replacing an incandescent light bulb with a CFL is not just a matter of screwing out one lamp and screwing in the other. While the CFL thread fits the lamp holder socket, the lamp does not always suit the luminaire—and it is not uncommon for users to reject the energy-saving CFL on purely aesthetic grounds.
Then suddenly in a world concerned about energy prices, everyone seems to be speaking of LED lamps as being the most energy efficient device available and outperforming fluorescent lighting by about as much as the latter once exceeded incandescent lighting. This is not actually the case. Today's LED lamps are not yet quite as efficient as fluorescent ones, their current potential use is limited, and their values and ratings are often being "tuned". It is a pity that incomplete and sometimes even misleading data became one of the most distinctive aspects in the promotion of LEDs. The facts are that LEDs do provide some features and characteristics which differ so much from all other lighting techniques that their real potential has yet to be discovered. This introductory Application Note aims at explaining what LEDs can do and what they cannot, how "tuning" in advertisements and even customer data sheets works, and where the real potentials lie.