Basic geometry are formulars and properties of basic shapes like rectangle, square, circle, triangle, and solid shapes like cuboid, cube cylinder etc.
The area, perimeter and volume of solid shape are properties that can be determined from this shape.
Perimeter is the sum of the whole side of the figure. Example the perimeter of a rectangle with 2 length and 2 width can be calculated by adding the whole 2 length and width.
The perimeter of the rectangle above is by adding all the sides.
perimeter = 4 + 4 + 2 + 2 = 12 cm
The area of the figure below is the amount of space of the boundary. The area of the rectangle below is length * width = 4 * 2 = 8 cm squared.