Issued to inform the public whenever severe or hazardous weather is either possible or occurring. The public, unfortunately, is not always informed on what a forecast means.

When I was younger, I could never discern between a watch and a warning. So, I've compiled a list of watches, warnings and advisories issued by the National Weather Service to warn people or stormy or shitty weather:

Wind advisory
High wind warning
Wind chill advisory
Flash-flood watch
Flash-flood warning
Severe thunderstorm watch
Severe thunderstorm warning
Tornado Watch
Tornado Warning
Snow Advisory
Winter storm warning
Blizzard Warning
Dense fog advisory

Warnings over the water:
Small craft advisory
Storm warning
Hurricane watch
Hurricane warning

Information gathered from Essentials of Meteorology by C. Donald Abrams