There are many different reasons why people color their hair. Some wish to lighten or darken their current color, cover gray hair, or follow various fashion trends by coloring their hair with unusual colors. Others may not like their natural hair color desire a change. Whether you color you hair yourself or go to a professional salon for coloring is a personal choice. There are different types of coloring processes that vary in the length of time that the color will last. Some people only color certain section of their hair, a process known as highlighting, while others prefer to color all of it. Temporary colors come in mousses, gels, and rinses that will shampoo out and generally produce less drastic results and damage to the hair than permanent hair color. Semi-permanent coloring, which is fairly easy to use, lasts through four to six shampoos and can enrich natural hair color and cover some gray. Permanent hair coloring products penetrate the cortex of the hair, lifting out the natural hair color and depositing new color. This type of hair coloring cannot be washed out and needs to be touched up every four to six weeks. If permanent hair coloring is used incorrectly or too frequently, it can damage your hair.