I have a ford explorer sport trac 2003. Todat when I was driving the radio cut of and then cut back on?

Then the radio won't come back on at all. I got to the light and the car slowed down I was able to coast it to a save place and park it. Then when I tried to start it up it didn't this click click click sound. What could this be. The battery is about five years old. Is it the battery or the starter?

Dedeed