Equiareal projection is a cartographic projection that maintains the area and shape of the Earth's surface. There are several synonyms for equiareal projection: equal-area projection, equivalent projection, authalic projection, and normal aspect projection. Each synonym highlights a particular aspect of the projection. For instance, equal-area emphasizes the preservation of area, equivalent emphasizes that the projection maintains angles and shapes, authalic emphasizes the mathematical formula used to distribute area, and normal aspect emphasizes the position and orientation of the projection. However, despite the different names, they all refer to a map projection that preserves the proportions of the Earth's surface areas.