the freezng of the blood in the viens of an aria
frostbite is a condition where your tissue is damaged on the cellular level. What occurs in the cell is simple. The cell is basicly a membrane filled with fluid (and many other things that aren't relevent to your question)when that fluid freezes the ice crystals damage the cell membrane.
those 2 people are right but when you get frostbite by standing in the cold too long you lose body heat in your ears,hands,nose and hands and what can happen is they start getting swollen and red and itchy. if you stay out longer they get puffy and eventually turn a whiteish then going up a blackish color. you get it off you have to cut it off by a doctor. ewwww i know. to see some really good pics go to google.com and type in frostbite and look at the pics. hope this helped. to prevent frostbite wear a coat,warm gloves or mittens, ear muffs, cozy socks, and STAY WARM!