Today you’ll find hair extensions in many different types and methods. There are also variances in the way hair extensions are prepared and in the method used to install them. A variety of hair extensions can be reused; however no hair extension last forever. Some methods last longer than others; nevertheless hair extensions are not safe for everyone’s hair. The three main categories for hair extension attachments are: Strand by Strand extensions, Clip-In extensions, and Weft extensions.