The color blue is one of the primary colors in the visible spectrum, located between green and violet. It is often associated with the sky and the ocean, which can appear in various shades, from light sky blue to deep navy blue. Blue light has a wavelength of approximately 450 to 495 nanometers, making it one of the shorter wavelengths visible to the human eye. In nature, blue is relatively rare compared to other colors. Many flowers, such as bluebells and hydrangeas, display this hue, while animals like the blue jay and blue poison dart frog showcase vibrant blue colors for communication or camouflage. Blue is also a popular color in art and design, symbolizing calmness and stability.