how to choose the led lamp?

Since traditionally the light output of individual light-emitting diodes is small compared to incandescent and compact fluorescent lamps, multiple diodes were and are often used together. In recent years, as "diode" technology has improved, now "high power" light-emitting diodes with higher lumen output are making it possible to replace A19, MR16, PAR, and other incandescent, halogen, and even fluorescent lamps with LED lamps. In other words LEDs can be made interchangeable or retrofitted with other types of traditional lamps. Diodes use direct current (DC) electrical power, so LED lamps must also include internal circuits to operate from standard AC voltage.

A light-emitting-diode lamp is a solid-state lamp that uses light-emitting diodes (LEDs) as the source of light. The term "LED lightbulb" is also colloquially used. "LED lamp" may in general refer to organic light-emitting diodes (OLED), or polymer light-emitting diodes (PLED) technologies as well as conventional semiconductor light-emitting diodes; although the OLED and PLED technologies are not yet commercially available.

LEDs are damaged by being run at elevated temperatures, therefore LED lamps typically include heat management elements such as heat sinks and cooling fins. LED lamps offer long service life and high energy efficiency, but initial costs are higher than those of fluorescent lamps.