Chaikin Money Flow (the CMF Indicator) was created by Marc Chaikin in the early 1980s as a way to measure the accumulation (buying pressure) vs. distribution (selling pressure) of a stock over time.

Chaikin Money Flow is displayed as a green/red oscillator around a 0-line, ranging from +100 to -100, with green regions representing net buying pressure, and red regions representing net selling pressure.

Because of the way the calculation was designed, money flow persistency (significant regions of green or red over a 6-9 month period), can be signs of accumulation or distribution by major institutions which have a disproportionate effect on future price movement. 

This is true even though the calculation looks only at price/volume activity, rather than directly monitoring institutional order flow.
A short-term money flow divergence —where price rises but Money Flow stays negative, or vice versa—can indicate an increased risk of a short-term reversal.