In map projection, equal-area maps preserve area measure, generally distorting shapes in order to do that. Equal-area maps are also called equivalent or authalic. An equal-area map projection cannot be conformal, nor can a conformal map projection be equal-area.

What is the meaning of equal-area?

of a map projection. : maintaining constant ratio of size between quadrilaterals formed by the meridians and parallels and the quadrilaterals of the globe thereby preserving true areal extent of forms represented.

What is an equal-area property?

The equal-area projection retains the relative size of the area throughout a map. So that means at any given region in a map, an equal-area projection keeps the true size of features. While equal-area projections preserve area, it distorts shape, angles and cannot be conformal.