**The lateral area of a pyramid is the total surface area of the pyramid excluding the base.** The formula for the lateral area of a regular pyramid is half the slant height multiplied by the perimeter. If the pyramid is irregular, calculation of the lateral area involves more complex equations and depends on the shape of the base.

A pyramid is regular when the base is a regular polygon, which is a shape in which all sides and angles are equal, such as a square or an octagon with eight 45-degree angles. The most famous pyramids in the world, the Great Pyramids of Giza in Egypt, for example, are regular pyramids because they have square bases.

A pyramid is constructed by connecting a base to an apex, which is the pyramid's highest point. The height of a regular pyramid is the distance from the apex to the base. The slant length is the distance from the apex to the midpoint of one of its bases. The perimeter of the pyramid is the sum of the length of all the sides of the base. When measuring for the lateral area, it's important not to confuse it with the surface area of the pyramid, which is the sum of the lateral area and the base area.