Divergences are considered to be pretty strong trend reversal signals. Divergence happens when the price action and the indicator in this case the histogram moves in the opposite directions. For example, the price action makes a new high while the indicator makes a new low or the price action makes a new low while the indicator makes a new high.
When divergence between the price action and the indicator develops, it means a potential trend reversal in the market. MACD is a very versatile technical indicator that can be used to trade these divergence patterns.