Monochromatic color schemes are a popular choice in website design, as they create a cohesive and harmonious look. They consist of different shades and tones of a single color, which can evoke a sense of calm and professionalism. This design approach can also enhance readability and make the website visually appealing. Key considerations when using a monochromatic scheme include selecting the right shade of the main color and ensuring contrast for text and other elements to maintain readability.