Is it the battery or the starter? This is one of those questions and situations where you could ask ten different people and possibly get almost ten different answers. Adding more insult to injury is you would probably only get one or two “yes” or “no” answers – the rest would be “well… it depends…”
Before we even give you a firm answer, we’d have to ask some additional questions – for example did you hear only one click, or was it a rapid clicking sound when you turned the key? If you heard the rapid clicking noise, almost like a high pitched machine gun, then chances are the battery needs to be replaced or at minimum a healthy recharge. If you heard just one click, then it most likely is the starter.
You have to be careful though – some people will tell you if the battery is dead, nothing on the car would work. That’s only true to a point. There may be enough juice in the battery to power the interior lights, the fan, the radio, and even the headlights. They only need a certain amount of amperage to run and it’s not a heck of a lot. In order to start a vehicle’s engine, a great deal more is required. So, be careful not to rule out a part you may think is the problem!
Lastly, if you have an appointment for service work to be done to replace either part, be sure to have the entire starting as well as the charging system checked. A worn out or intermittent alternator (a bad diode in the alternator) may result in insufficiently recharging the battery, or a bad ground may be putting a draw on the battery thus draining it prematurely.