A point is a location in a buffer where editor commands take effect. The current point is generally the location between the character indicated by the cursor and the previous character (that is, it actually lies between two characters). Many types of commands (that is, moving, inserting, deleting) operate with respect to the current point, and indeed move that point.
Each buffer has a current point associated with it. A buffer that is not being displayed remembers where its current point is and returns the user to that point when the buffer is redisplayed.
If the same buffer is being displayed in more than one window, there is a point associated with the buffer for each window. These points are independent of each other.