A life jacket is a garment designed to save a person's life in the event of an accident in water. There are three main types of life jacket: Type I, Type II, and Type III. Type I life jackets are also known as offshore life jackets. They are designed for use in rough water, far from shore. They are the most bulky and uncomfortable of the three types, but they are also the most effective. Type I life jackets will keep you afloat even if you are unconscious. Type II life jackets are also known as near-shore life jackets. They are less bulky than Type I life jackets, and thus more comfortable to wear. They are not as effective as Type I life jackets, but will still keep you afloat if you are unconscious. Type III life jackets are also known as flotation aids. They are the least bulky and most comfortable of the three types, but they are also the least effective. Type III life jackets will not keep you afloat if you are unconscious.