Other projections
Many projections are conceptually created by projecting from one geometric shape (a sphere) onto another (a cone, cylinder, or plane). However, other projections are not related as easily to a cone, cylinder, or plane.
Modified projections are altered versions of other projections (for example, the Space Oblique Mercator is a modification of the Mercator projection). These modifications are made to reduce distortion, often by including additional standard lines or changing the distortion pattern.
Pseudo projections have some of the characteristics of another class of projection. For example, the sinusoidal projection is called pseudo cylindrical because all lines of latitude are straight and parallel and all meridians are equally spaced. However, it is not truly a cylindrical projection because all meridians except the central meridian are curved. This results in a map of the earth having an oval shape instead of a rectangular shape.
Learn more about the sinusoidal projection.
Other projections are assigned to special groups, such as circular or star.