Market appreciation is the gradual increase in value of every property in the market. It is driven by large macroeconomic factors such as population growth, job growth, unemployment, taxes, and other factors typically outside of the direct influence of the investor.
While market appreciation is a gradual increase in value, forced appreciation comes in a much shorter timeframe. It is appreciation that comes from improving the property or improving the management of a property.
Forced appreciation typically is incremental and occurs with bursts of activity. It can even be paired with market appreciation for more dramatic results.
Forced appreciation is repeatable. By creating 30% of value, that is something you can then go to a bank and refinance based off of. You can then put much of that increased value back into your pocket to invest again.