Graph is a group of points (nodes) connected through lines (edges). The graph theory which is one of the most important areas in discrete mathematics; described as the branch of mathematics which concern with organizing the structural setting of connected objects, representing its complex networks and the modelling process of the relationship between its nodes.
One of the most simple ideas of graphs is to find a path between all nodes, without over-pass an edge twice(the house of Santa Claus). and also we know the short shortest path problem, which follow the same logic of graph theory, the algorithm we use widely in maps and search algorithms.
Graph theory is used widely in solving practical issues in many areas of knowledge, including biology, physics, chemistry, sociology, and information systems and computer science.
In Design Computing, Graphs are used to help in representing and solving many design problems, such like flat-paths drainage, shortest path to destination in mapping and urban planning, in addition to space syntax and allocation algorithms.