HID are commercial lamps that are used in shopping centres, street lighting, factories, sporting venues, etc
HID lamps have differing properties and most times the application will determine the specific lamp type required
Metal Halide Lamps
Metal Halide Lamps offer high lumens per watt performance, excellent colour rendition, long service life and good lumen maintenance (the level of light output over the life of the lamp)
High Pressure Sodium Lamps
High Pressure Sodium Lamps are very energy efficient. Mercury and sodium vapours produce a yellow/orange light with extremely good lumens per watt performance. Although they tend to render colours poorly they have an exceptionally long lamp life (up to 40,000 hours)
Mercury Vapour Lamps
Mercury Vapour Lamps are the oldest HID technology. The light within the arc is bluish making it poor for rendering colours accurately. Because of this, a phosphor coating is sometimes applied to alter the colour temperature and to improve colour rendering. These lamps also have very poor lumen maintenance over lamp life
Strengths
Usually very economical to operate
Long to extremely long life (up to 56000 hrs)
High light output
Weaknesses
Control gear required for operation
Expensive to install and re-lamp
Colour can be poor and variable with certain lamps
Lighting 
