I do not own a horse yet but have been riding for a couple years and I am wondering how the whole deworming your horse works? I figured I should learn this stuff BEFORE purchasing

Like how often do people deworm there horses? Do you use the same wormer everytime? Because I think I heard a lady say you use a different worming depending on the time of year or something????? Not really sure but any way I am curious to learn this proper care!