Vertical means straight up and down, like a flagpole standing tall or the edge of a door. When something is vertical, it runs from top to bottom rather than side to side.

Think of a building's walls: they're vertical, rising straight up from the ground. When you stand up straight, your body forms a vertical line from your head to your feet. Trees grow vertically toward the sky, and rain falls vertically to the ground.

The opposite of vertical is horizontal, which means lying flat or running side to side. A tabletop is horizontal, while its legs are vertical. Understanding this difference helps in math class when you learn about graphs: the vertical axis goes up and down (usually labeled with a y), while the horizontal axis goes left to right (usually labeled with an x).

In rock climbing, a vertical face is a section of rock that goes straight up, making it especially challenging. Mountain climbers might say they climbed vertically for 500 feet, meaning they went straight up that distance.