The three-dash graphic that is clicked or tapped to display a menu on screen. The graphic analogy is a list, and the metaphor is the three-layer hamburger: bottom bun, meat and top bun.
Not Much to Look At
Just three horizontal lines. The three dots on the right are also a common menu icon.
A Real Hamburger Icon
In Windows 10 Tablet mode, a hamburger icon is displayed in the upper left corner of the screen.