Feet are a complicated part of the body since there are numerous small bones that are joined together by a lot of ligaments and moved by a lot of muscles. Furthermore we take the bodyweight on the feet and subject it to so many stresses and strains. To make it even worse we place the foot inside the artificial environment of a shoe. It's for this reason that the profession of podiatric medicine exists since there is just so much which will go wrong with the foot and associated structures. Podiatric physicians make use of a lots of different interventions to treat problems of the feet and lower limb.
Foot orthotics are often used to manage the wide array of conditions that may go wrong with the foot. The purpose of foot orthotics are to improve alignment of the feet towards a more corrected normal alignment or to decrease the stress in structures of the foot which might be causing symptoms so that they can improve. The foot supports achieve this via having different design features which are meant to match the foot. A customized foot orthotic will do that. However, over the counter orthotics can do this, generally by chance. They may or might not match the foot of the person with them in contrast to a custom made insert will. There are many different designs that can be varied, like the elevation of the mid-foot ( arch ) and also the level of shock absorption. There are even designs referred to as Kinetic wedge and Cluffy wedge.
At times the more affordable over-the-counter type supports are better and other times the custom ones are more effective. It will all depend upon the type of the problem, the foot type and shape as well as the advice of a good podiatrist in regards to what is the best choice. When you have an issue with your feet and think you need some foot supports, then go to a good podiatrist.