You have flatfeet when the arches on the inside of your feet are flattened, allowing the entire soles of your feet to touch the floor when you stand up.
A common and usually painless condition, flatfeet can occur when the arches don't develop during childhood. In other cases, flatfeet develop after an injury or from the simple wear-and-tear stresses of age.
Flatfeet can sometimes contribute to problems in your ankles and knees because the condition can alter the alignment of your legs. If you aren't having pain, no treatment is usually necessary for flatfeet.