An information sign is a very legibly printed and very noticeable placard that informs people of the purpose of an object, or gives them instruction on the use of something. An example is a traffic sign such as a stop sign.
Information signs have been growing in visibility due to the explosion of sign technologies. For hundreds, if not thousands, of years signs were crafted out of wood. Words and images were then hand-painted on the sign. The other traditional way of creating signs dealt with individual constructed letters carved from wood, molded or wrought from metal, which were then individually placed in the appropriate sequence.
While both of these methods are still employed, technology has moved in around them. Woodworking machinery can now be controlled by computers, leading to much greater consistency. Molded signage has changed dramatically with the advent of plastics, which are far more flexible than metal as well as significantly cheaper to produce. Additionally, altogether new sign technologies have come into being, such as computer-cut vinyl signage.
The most common relative directions are left, right, forward(s), backward(s), up, and down. No absolute direction corresponds to any of the relative directions. This is a consequence of the translational invariance of the laws of physics: nature, loosely speaking, behaves the same no matter what direction one moves. As demonstrated by the Michelson-Morley null result, there is no absolute inertial frame of reference. There are definite relationships between the relative directions, however. Left and right, forward and backward, and up and down are three pairs of complementary directions, each pair orthogonal to both of the others. Relative directions are also known as egocentric coordinates.