Over time, shifting markets and recurring contributions to your account can send your portfolio and targeted risk level off course. Rebalancing adjusts your portfolio to keep it on track to help you reach your goals. Keep in mind that rebalancing your portfolio may have tax consequences.
If you choose to manage your investments on your own, it's important to rebalance your portfolio along the way.
If someone else is handling your investments (like in a mutual fund or digitally managed portfolio), they typically take care of rebalancing.