In ergonomics, there are a few rules that apply to the way we should be sitting. These are to have our hips higher than our knees with our feet flat on the floor. The armrests of the chair should be in-line with the top of the desk. This is the ideal position. Sometimes though, we cannot achieve this position if the desk is too high. This is where a foot rest comes in. It allows the user of the chair to sit higher, while supporting their feet, preventing pressure on the underside of the legs.