Color is one of the main distinctions in types of flares. White flares are for signaling in non-emergency circumstances -- say, for finishing a race -- and red flares are supposed to indicate an emergency. Red flares owe their distinctive color to the presence of strontium nitrate.
There are also aerial signals and hand-held signals, both of which are what they sound like. Aerial signals are generally more useful for attracting the attention of rescue craft. They fire up into the air, providing a brighter spectacle that generally illuminates an area. They also may hang in the area for a long time if they're parachute flares (more on them soon).
Hand-held signals are more useful for signaling your exact location. They may be visible by other surface craft for 3 to 5 miles (4.8 to 8 kilometers) [source: Orion Safety Products].
Parachute flares are flares that deploy small parachutes when fired into the air. These flares can hover in the air for 25 to 30 seconds [source: Orion Safety Products].
SOLAS flares -- SOLAS is an acronym for safety of life at sea -- are more powerful flares often used by oceangoing vessels. In fact, if you're a commercial fishing boat operating 50 miles (80 kilometers) or more offshore, SOLAS flares are required -- three parachute flares, three smoke flares and six handheld flares [source: West Marine]. There are similar legal requirements to carry SOLAS flares if you're racing in an official sailing event.
Now that you've learned about different types of flares and signals, let's learn how to use them.