This is a diagram of which shapes fall into which categories based on the properties of that shape. For example, a square is a special kind of 2-D, quadrilateral, trapezoid, parallelogram, rectangle and rhombus, so it is at the end of that trail of categories.
The chart is meant to eliminate confusion about which shapes fall into which categories. I found a lot of students had a hard time grasping "wait, a rectangle is a type of parallelogram? and a square is a type of rectangle?", so I felt the need for a visual to clarify.
I used this chart in a center I created called "Secret Shapes". It had a booklet I made with clues on each page for a different shape found on the shape chart. Students would take a laminated copy of the shape chart and a dry erase marker and cross off shapes that didn't fit the clues as they were read. Eventually, the clues narrowed it down to one shape. The student reading the book would check the work of the student guessing with the chart, and then they would switch.
Example of clues:
1) I am flat.
2) I have 3 sides.
3) I have a 90 degree angle.
Answer: Right Triangle
1) I have depth.
2) I have 6 sides and 8 corners.
3) All of my sides are the same.