system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is stickiness and do we have a measure for stickiness?
gpt
There are several different measurements for adhesion. Peel is when you pull it off at an angle and measure the force it takes , shear is when you try to slide the two adhered surfaces in opposite directions and again, measure the force it takes,  and tack is measured by rolling a small steel ball across the surface of a pressure-sensitive adhesive from a pre-determined height/incline and measuring the distance the ball rolls across the adhesive surface.

Usually, an adhesive with high shear will have low peel and vise versa.

*Edited for clarity.