A primary care physician is a doctor who provides most of your primary and preventive care, and who is available to refer you to specialists if necessary. While there’s no requirement to designate a primary care physician and you can change providers at any time, most people have a primary care physician overseeing their care. While obtaining a referral to see a specialist isn’t necessary, primary care physicians can be a valuable resource in identifying the type of specialist you need to see and providing a list of specialty providers who might work well for you.