This paper presents a noncooperative model of network formation, where social networks are formed through individual decisions that balance the costs of forming and maintaining links against the potential rewards. The authors assume that a link with another agent provides access to benefits available through the latter's links, with the value of these externalities depending on the decay/delay of indirect links. A key feature of their model is that the costs of forming a link are borne only by the initiating agent, allowing the network formation process to be formulated as a noncooperative game. The paper characterizes the architecture of equilibrium networks and studies the dynamics of network formation. It finds that individual efforts to access benefits from others lead to the rapid emergence of equilibrium social networks, which often have simple architectures such as wheels or stars. These networks are also socially efficient in many cases. The authors also explore both one-way and two-way benefit flows and assume frictionless benefit transfer across individuals. They show that Nash networks are either connected or empty, but connectedness is permissive, allowing for a wide range of Nash equilibria. To address the multiplicity of Nash equilibria, they introduce a stronger equilibrium concept, focusing on networks supported in a strict Nash equilibrium.This paper presents a noncooperative model of network formation, where social networks are formed through individual decisions that balance the costs of forming and maintaining links against the potential rewards. The authors assume that a link with another agent provides access to benefits available through the latter's links, with the value of these externalities depending on the decay/delay of indirect links. A key feature of their model is that the costs of forming a link are borne only by the initiating agent, allowing the network formation process to be formulated as a noncooperative game. The paper characterizes the architecture of equilibrium networks and studies the dynamics of network formation. It finds that individual efforts to access benefits from others lead to the rapid emergence of equilibrium social networks, which often have simple architectures such as wheels or stars. These networks are also socially efficient in many cases. The authors also explore both one-way and two-way benefit flows and assume frictionless benefit transfer across individuals. They show that Nash networks are either connected or empty, but connectedness is permissive, allowing for a wide range of Nash equilibria. To address the multiplicity of Nash equilibria, they introduce a stronger equilibrium concept, focusing on networks supported in a strict Nash equilibrium.