An angle is formed by two rays that have a common origin.

Two intersecting lines form 4 angles. The opposing ones are congruent and the neighboring ones have the sum 180 (are supplementary angles).

AEC = DEB
AED = CEB

AEC + AED = 180
CEB + BED = 180
AEC + CEB = 180
DEA + BED = 180

If we have a point on a line then that point cuts the line in two rays.
So a ray are all the points on the line that are on the same side of a point that is on that line.

The circle is a very important object in geometry.

A circle represents the set of points that are at the same distance of another point (named the center of the circle).

For example if A is a point and B is at a distance r of A then this is how the circle of center A and ray r looks like: