Bottom line
Your Career Retirement Credit Report (CRCR) is the running record of every retirement point you have earned across your whole career. It is what selection boards and reenlistment evaluators look at to measure your activity, and it feeds the math on your retirement eligibility and retired pay. Once a year you have to certify it (confirm it is correct), and exactly how that works depends on whether you are IRR/IMA, SMCR, or AR. If anything is wrong, you fix it by hand with black ink and back it up with documentation.
What it means for you
This is the report that protects your retirement. The CRCR is the career-long summary; the Annual Retirement Credit Report (ARCR) is the one-year snapshot it is built from (see Chapter 4, Section 1 for how points are earned and recorded). Errors here can cost you a good year or shift your dates, so the annual certification is not a formality. MOL (Marine Online) will keep nagging you until your CRCR is certified, so the fastest path is usually self-certification through MOL. If you are ordered to active duty for more than 30 days, your CRCR has to be screened and corrected before you go, because the system uses it to calculate your Armed Forces Active Duty Base Date (AFADBD).