Point

A point is a theoretical location that has neither width, height, nor depth and  describes exact location in space. A point is represented in technical drawing as a small cross made of dashes that are approximately 3 mm long. As shown in figure 4, a point is used to mark the locations of  centers and loci, the intersection ends, middle of entities

 

Figure 4. shows the various use of points.

Line

A line is a geometric primitive that has length and direction, but no thickness. Lines may be straight, curved or a combination of these. As shown in figure 5, lines have few important relationship or conditions, such as parallel, intersecting, and tangent.  Lines can be of specific length or non-specific length. A Ray is a sStraight line that extends to infinity from a specified point.

 

 

Figure 5. Relationship of one line to another line or arc