Illustrated · 1 min
Angles are what happens when two lines intersect
When two lines (or segments, or rays) intersect, they form angles. Every corner (a.k.a. vertex) on every shape you've ever seen forms an angle, too!
How open an angle is is called its measure, which can be expressed in degrees or radians. You can use a protractor to measure angles.
Angles have three points in their names: a point on one of the lines that make them, the point where they intersect, and a point on the other line. We can call the angles in the image above BCA (or ACB) and FED (or DEF). You can use small marks (like the little arcs above) to represent information about angles.
There are tons of different types of angles, and loads of words to describe angles' relationships to each other. The more of them you learn, the easier it'll be to think and talk about geometry!