Yards can become more easily used sometimes with the addition of sidewalks. Screen walls can make them more pleasant to view.
The first picture shows a rear yard with an open view of pool equipment. The second picture shows the same view after a screen wall and sidewalk were added.
Retainer walls are used to make a sloped area flatter. They can be beautiful as well as functional.
The retainer wall footing resists the tipping forces on a retainer wall using the weight of the retained material.
The vertical wall is poured after the footing using forms which are tied together so that the concrete sideways forces equal each other out.
This completed wall is functional and was later painted very nicely with pictures of custom cars.