Why does my bike keep slipping gears and how can I fix it?

Your bike may be slipping gears due to issues with the gear shifters, derailleur, or chain. To fix it, you can try adjusting the tension on the derailleur cable, cleaning and lubricating the chain, or replacing worn-out components. If the problem persists, it may be best to take your bike to a professional mechanic for further inspection and repair.