Hair extensions have exploded since Jessica Simpson introduced a line of clip-in hair extensions. Transforming short hair to long in a matter of minutes, clip-in hair extensions are great for those who want to try it out without a lasting commitment. Clip-in hair extensions have to be removed every night and re-applied in the morning. When they first came out, clip-in and semi-permanent extensions were only used by celebrity hairdressers on their famous name celebrities. Over the past couple of years hair extensions have made it into mainstream hair salons and are offered throughout the nation.