The foot is a complicated part of the body as there are so many small bones that are joined together by so many ligaments and controlled by so many muscles. On top of that we bear weight on the foot and subject it to so many pressures. To make it even worse we put the foot inside the unnatural environment of a shoe. It is for this reason that the profession of podiatry exists as there is just so much that can go wrong with the foot and related structures. Podiatrist use a wide range of different interventions to treat problems of the foot and lower limb.
Foot orthotics are often used to treat the wide array of problems that can go wrong with the foot. The aim of foot orthotics are to change alignment of the foot towards a more corrected normal position or to reduce the load in structures of the foot that are painful so that they can get better. The foot orthotics achieve that via having different design features that are supposed to match the foot. A custom made foot orthotic will do that. However, over the counter supports can do that, often by chance. They may or may not match the foot of the person using them whereas a custom made one will. There are many different designs that can be varied, such as the height of the arch and the amount of cushioning. There are even designs known as the Kinetic wedge and Cluffy wedge.
Sometimes the cheaper over-the-counter type supports are better and other times the custom made ones are better. It will all depend on the nature of the problem, the foot type and structure as well as the advice of a good clinician as to what is the better option. If you have a problem with your feet and think you need some foot orthotics, then see a good podiatrist.