Orthotics are a common treatment used for a variety of conditions. Broadly, there are two categories of orthotics provided by podiatrists, prefabricated and customised.
Prefabricated orthotics are mass produced and sized to fit a person's foot. There are a very wide variety of prefabricated orthotics that are manufactured, with some being better than others. For most people, prefabricated orthotics that are correctly fitted can be very effective to reduce pain and improve function (e.g. for short term conditions).
Customised orthotics are made by taking either a mould, an impression or a laser scan of a person's feet. This is then combined with a prescription by a podiatrist, that specifies what features the orthotic should have. Customised orthotics can be fabricated from a variety of materials, and have endless possibilities in terms of shape and function.
A podiatrist will be able to help you understand which type of orthotic will be best suited for you and the goals you want to achieve. One major consideration is cost, and there is a price difference between each option and the podiatrist can factor this in when discussing options with you.