An idealized mathematical object having a rigorously straight edge which can be used to draw a line segment.

What are examples of straight edge?

Most would agree that to be considered straight edge, you must abstain from consuming alcohol and drugs, smoking cigarettes, and engaging in sex outside of caring relationships, but many 'edge' individuals choose to abstain from other substances as well.

What is a compass and straightedge in math?

Straightedge and compass construction, also known as ruler-and-compass construction or classical construction, is the construction of lengths, angles, and other geometric figures using only an idealized ruler and a pair of compasses.