Theory:

When we look around us, we find objects of different sizes and shapes.

Shapes come with different measurements such as length, breadth, height, depth and so on, and they are classified into two-dimensional and three-dimensional shapes.

Dimension:
Measurement of the shapes from a certain angle or direction is called dimension.
In the case of shapes and objects, dimensions include length, breadth, height and so on.
Two-dimensional shapes
The closed figures drawn on a flat-surface or on a plane are two-dimensional shapes. The sides of these shapes can contain straight or curved surfaces. The shapes can have '$$n$$' number of sides.
These shapes will have length and breadth, hence becoming two-dimensional.

$$2$$-D shapes are also called as plane figures.

Some of the two-dimensional shapes include:

 Shape Name Circle Triangle Square Rectangle Ellipse Quadrilateral

Three-dimensional shapes
Our entire world is made up of objects that occupy space. Any object or a shape that occupies space is three-dimensional.
The $$3$$-D figures are also called as solid figures.

Some of the three-dimensional shapes include:

 Shape Name Sphere Cube Cuboid Cylinder Pyramid Cone