The built-in cabinets are great options to take advantage of spaces, they are custom-made and you can determine the necessary shelves and niches.
Under the stairs
This space is one of the most difficult to use, the built-in closet is ideal, and may have a library, and various niches.
There is also the option of making it open as a shelf, taking advantage of corners and niches in the environment.
Another advantage of the built-in is that it is possible to create environments, such as a home office.
For the kitchen it is also wonderful because, as it goes from the ceiling to the floor and openings in the front, it is possible to have a storage system with a lot of space.
Super common in American homes this type of cabinets, it is generally used for closets
It is also super practical, as you can use the entire length of the wall and make one, and depending on the color, it will be very discreet in the environment.