This chapter discusses the key principles of noncooperative game theory with the aid of several examples. To characterize a game, several items must be specified; for example, the players are the agents that make decisions. For a mathematical solution to a game, it is also important to make assumptions on the player's rationality, regarding questions such as: Will the players always pursue their best interests to fulfill their objectives? Will the players form coalitions? Will the players trust each other? The chapter proceeds by using the rope-pulling game to examine the motivation and implications of assuming a noncooperative vs. cooperative framework. It also considers the robust design problem and its formalization into a resistive circuit design game, a network routing game, and the Nash equilibrium before concluding with a practice exercise related to the network routing game, complete with solution.