What does a positive slope indicate about the direction of a line?

A positive slope indicates that as you move along the line from left to right, the value of the y-coordinate increases. This means that the line rises as it extends horizontally, giving it an upward direction. In more practical terms, for every unit you move to the right on the x-axis, the line moves up by a certain amount on the y-axis. Therefore, a positive slope clearly signifies an upward trend in the graph, visually presenting itself as the line pointing up. This understanding is fundamental in graphing, as it helps interpret and analyze relationships between two variables.

The other options describe different characteristics of lines that do not align with the concept of a positive slope. For instance, a line that points down corresponds to a negative slope, while running parallel to the y-axis would indicate vertical movement, which is not measured by slope. Similarly, a line that runs sideways indicates no vertical change, corresponding to a slope of zero.