Think of your p5.js canvas like a treasure map.
Coordinates tell the computer exactly where to draw something.
Unlike math class (where (0,0) is at the bottom),
p5.js starts at the top-left corner:
(0,0) β top-left corner
(0,0) (100,0) (200,0)
β---------β-----------β
(0,0)
β
|
β (0,100)
|
β (0,200)