See Section 14.4.1 for points in space.
In the 2-d geometry screen in point mode, clicking on a point with the left mouse button will choose that point. Points chosen this way are automatically named, first with A, then B, etc.
Alternatively, the point command chooses a point.
Example.
Input:
or:
or:
Output:
The marker used to indicate the point can be changed; see Section 13.3.2.
If the point command has two numbers for arguments, at least one of which is complex but not real, then it will choose two points.
Example.
Input:
or:
Output:
There are two points named A; one with affix 1 and one with affix 2i.