Here are the key points about dimensions:
- Two-dimensional (2D) objects can be described with length and width. They exist on a flat plane and do not have height or depth. Common 2D shapes include circles, squares, triangles, etc.
- Three-dimensional (3D) objects can be described with length, width, and height. They exist in three-dimensional space and have volume. Common 3D shapes include cubes, spheres, cylinders, etc.
- To understand an object's dimensions, you need to consider how many axes of measurement it has. 2D objects have two axes (length and width) while 3D objects have three axes (length, width, and height).