Why does ketchup sick to the sides when you pour it out?

Ketchup sticks to the sides of the bottle due to its viscosity and the adhesive forces between the ketchup and the bottle's surface. When poured, the thick consistency causes it to cling rather than flow freely. Additionally, the molecular structure of ketchup, which includes water, vinegar, and thickeners, contributes to its tendency to stay attached to surfaces. This phenomenon is often referred to as "stickiness" or "cohesion."