Graph Theory

In Graph Theory, a graph is an accumulation of dots that may or may not be joined to  each  other by lines. It doesn't amount how big the dots are, how long the curves are, or whether the curve are straight, curved, or squiggly. The "dots" needs not to be round! 

All that matters is which dots are joined by which lines.

Two dots can alone be affiliated by one line. If two dots are joined by a line, it's not "legal" to draw another line joining them, even if that line stretches far  from the first one
 Graph theory applications: Graph theory  plays an important role in the design, analysis, and testing of computer programs. It is important for the fact that flow of control and flow of data for any program can be expressed in terms of directed graphs.