Is it my starter?

If your car had a dead battery in the morning, and a jump to a good battery got it running, sounds like you need to check out the battery and charging system. Will it restart if you jump it again? You need to have a good battery and charging system to make your starter work so I don't know what to say abut the starter itself yet. If the starter spins and doesn't turn the motor over with a good battery, then you need to look at the starter. When you pull the starter out to visually check the drive gear, look at the ring gear on the flywheel all around for missing teeth. You could have a combination of problems but make sure your battery and charging system are good before replacing the starter. I usually have a voltmeter at least in my hand when I diagnose these things. If you put a voltmeter on the battery or the starter cable (better), you should have about 12.4 volts with the key on and at least 10.5 volts when the starter is engaged.