Adjusted Funds From Operations — the gold standard cash flow metric for REITs.
FFO adds back depreciation (since real estate often appreciates) and removes property sale gains. AFFO goes further, subtracting recurring maintenance CapEx and other non-cash adjustments to show true recurring cash flow. AFFO is considered the best measure of a REIT's ability to pay dividends.
A healthy REIT typically pays 70-85% of AFFO as dividends. Above 90% leaves little cushion; below 60% suggests the dividend could be raised.