Describe what a slope of zero indicates about a line.

A slope of zero indicates that the line is horizontal. This means that regardless of how far you move along the x-axis (the horizontal direction), the value of y (the vertical direction) remains constant. In practical terms, no matter what value you choose for x, the output for y does not change, which translates into a flat, horizontal line on a graph.

In contrast, a line with a positive or negative slope would show an increase or decrease in y values as x changes, indicating a tilting line rather than a flat one. Therefore, a zero slope uniquely signifies that the line runs left to right without ascending or descending, providing visual representation and capturing the idea of a constant value across its length.