A Required Minimum Distribution (RMD) is a regulation that requires you to begin withdrawing funds from your IRA once you reach a specific age. Even if you would prefer to keep the money in your IRA, you must start taking distributions when you reach the designated age.
For more details on RMDs and how they apply to various types of IRAs, please visit the linked IRS page below:
Retirement Topics — Required Minimum Distributions (RMDs) | Internal Revenue Service (irs.gov)