Abstarct: Assume that G=(V,E) is a connected undirected graph and r≥1 is an integer number.Let C⊆V be a subset of vertices. We define a ball of radius r centered at a vertex v to be the set of vertices in V that are at distance at most r from v. If for all vertices v∈V, the sets B_r (v)∩C are all nonempety and distinct, then we call C an r-identifying code. If for all vertices v∈V∖C, the sets B_r (v)∩C are all nonempety and distinct. then we call C an r-locating-dominating code. The identifying and locating-dominating code are two of the most fundamental and well-studied parameters in graph theory as well as a coding theory. In this thesis,we study the construction of the identifying and locating-dominating codes of graphs. We also find a a lower bound for the cardinality of a minimum identifying code of a graph G.