These are highlights and lowlights placed within their natural hair color. Highlights is anything lighter than the natural color and lowlights is anything the same or darker then the natural color. This is generally done to create more dimension and/or contrast or to simply place the natural color back through overly highlighted hair. Depending on how they are placed, a highlight/lowlight combination can also be used to make the hair color look completely natural with the more colors you use. Click on pictures for more details.