Why is the starter just spinning when you turn key?

If the starter is just spinning when you turn the key, it may indicate that the starter gear is not engaging with the flywheel, which could be due to a faulty solenoid, a worn-out starter motor, or a defective flywheel. Additionally, insufficient battery power or poor electrical connections can prevent proper engagement. It's advisable to check the battery voltage and connections first, and then inspect the starter and flywheel for any damage or wear.