The equation "y = c" represents a horizontal line on a graph, where "y" is the dependent variable and "c" is a constant value. This means that no matter what value "x" takes, "y" will always equal "c." For example, if c is 3, the line will be at the height of 3 on the y-axis, indicating that every point on this line has a y-coordinate of 3. In this equation, "c" can be any real number, such as 0, 1, or −5. The simplicity of "y = c" makes it easy to understand and visualize, as it shows that the output remains unchanged regardless of the input. This concept is fundamental in mathematics and is often used in various fields, including physics and economics.