Which way is which?
Horizontal is left to right
Vertical is down and up
An easy way to remember HORIZONTAL is that the HORIZON is left<~~>right.
http://www.answers.com/horizon
http://www.answers.com/horizontal
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To determine which way is horizontal and which way is vertical, you can use a helpful mnemonic device. First, let's understand the definitions:
Horizontal: Referring to a line or direction that runs parallel to the horizon or the ground. It goes from left to right or right to left.
Vertical: Referring to a line or direction that is at a right angle to the horizon or parallel to something that stands upright, like a wall. It goes from up to down or down to up.
To remember which is which, you can think about the word "horizon" to remind you that horizontal goes from left to right or right to left, just like the horizon appears in our vision.
Similarly, vertical can be remembered by recalling something "standing upright" like a wall. It goes from up to down or down to up.
By association with these mnemonic references, it becomes easier to remember the difference between horizontal and vertical orientations.