On the stock market, when a stock opens a s significantly different price than the previous day's close, it is called a gap.
The market has a tendency to close gaps in price by revisiting the "missed" price region.
Even though bitcoin markets are open 24 hours, (so there are no actual "gaps") there are sudo-gaps, where the price action move too quickly for supply and demand to be fully established. Just like the stock market, bitcoin likes to close gaps. Look at the last 3 gaps on the chart!