Primary colors — blue, red and yellow — are the foundations of all other colors (black and white help with tone and value). But they are less common in interior design than their derivatives. You see lots of light yellow and different shades of blue; a ton of green. But you don't see as much of the true shades.

This might be because primary colors in their true forms are often associated with childhood and a floor covered in toys. But there is no reason they have to be babyish. Just ask Mondrian or Miró. Primary colors are the colors of modern art, comic books and pop art.

Primary colors have major impact, especially when they are used together. They are clear, straightforward and bold. You often see them combined with geometric shapes in modern design. But they are most often used in small doses — a painting here, a chair there — or in more muted derivations, like light blue, turquoise, pinks and burgundies.

In modern design, primaries go well with bright white and gray tones. But in other styles they can go a little more wild. You see them sometimes in richly patterned rugs.

Below are some rooms that go all out — primary colors or bust — and some that are more meditations on a theme, with lots of room for interpretation. All of them are brave and beautiful in their own way.