DO NOT do what that girl just said (leave the bleach in longer). It depends on the color you already have, if you've dyed your hair/highlights, if your roots are coming back, and how strong the bleach is! You don't want to slap bleach in your hair and leave it!! You can do extreme damage to your hair!! And if you leave it in too long, your hair will turn into a gooey mess!! Almost like over cooked noodles. And it your hair will fall out!!