Pressure in a straw

I was drinking water out of a straw today.  I started playing with it by suctioning water up it and then covering the top of the straw with my finger. I became mindful that the water stayed in the straw instead of falling back out like you would expect it to. This is because the pressure below my finger is pushing up at a higher pressure than what it would normally be if I didn't have the finger on top.  This pressure gradient makes the water stay in the straw instead of falling down.