Hair coloring is a popular form of self expression. Many people choose to go to a salon to have the service done professionally and several others prefer to use box color.
Box color seems to be the go to to cut down on expenses. However, box color is very harmful to the hair. On the box it shows images of hair color at different levels and how your color will look after the process. It does not thoroughly explain the color may vary based on the natural tone of your hair, the porosity of the hair, the condition of the hair, previous color etc.
Getting more scientific, box color blasts the cuticle open, while professional color opens the cuticle just enough for the color to penetrate into the cortex. What does that mean? The less the cuticle opens, the better. The more it opens, the hair is susceptible to damage such as split, porous, dull, lifeless hair.
With that being said don't take the inexpensive route. Go see a professional or in my case, a professional in training.