A hair weft is simply where a collection of strands of hair are attached together to create a natural looking piece of hair. A weft looks a bit like a small piece of a wig. The individual strands of hair could be attached together using fishing line, cotton or nylon. A weft which you attach to your head could range from 2 inches wide to 10 inches or more. Some wefts are manufactured 3 feet or longer and you can then cut the weft into pieces that suit you.