The paper by L. Susskind and E. Witten explores the holographic principle in Anti-de Sitter (AdS) space, focusing on the correspondence between string theory in AdS and super Yang-Mills theory. The authors address the holographic bound, which states that the boundary theory should have only one bit of information per Planck area. They argue that this bound is a consequence of the infrared (IR) effects in the bulk theory being reflected as ultraviolet (UV) effects in the boundary theory. This relationship, known as the IR-UV connection, is crucial for understanding the information density in the boundary theory. The paper begins by introducing the holographic hypothesis, which posits that a macroscopic region of space can be described by a boundary theory living on its boundary. The authors then discuss the specific case of Type IIB string theory on AdS5 × S5, which is dual to a 3+1-dimensional U(N) super Yang-Mills theory. They explain how correlation functions in the boundary theory can be expressed in terms of calculations in the bulk. The authors delve into the geometry of AdS space, representing it as a product of a unit four-dimensional spatial ball and an infinite time axis. They derive the relationship between the radius of the AdS space and the size of the gauge group in the boundary theory. They also discuss the IR-UV connection, showing how regulating the boundary area in the bulk theory is equivalent to regulating the UV cutoff in the boundary theory. In the third section, the authors make plausible assumptions about the information storage capacity of a cutoff field theory, leading to the conclusion that the number of degrees of freedom in the boundary theory is proportional to the area of the boundary. They further illustrate this connection by considering a thermal state of the boundary theory, which must represent an AdS Schwarzschild black hole. The paper concludes with general remarks on holography, discussing the nature of the mapping from the bulk to the boundary theory and the implications of the holographic principle in theories with a negative cosmological constant. The authors suggest that the holographic hypothesis may be sharpened for theories with zero or positive cosmological constant, but acknowledge the need for new ideas to address this case.The paper by L. Susskind and E. Witten explores the holographic principle in Anti-de Sitter (AdS) space, focusing on the correspondence between string theory in AdS and super Yang-Mills theory. The authors address the holographic bound, which states that the boundary theory should have only one bit of information per Planck area. They argue that this bound is a consequence of the infrared (IR) effects in the bulk theory being reflected as ultraviolet (UV) effects in the boundary theory. This relationship, known as the IR-UV connection, is crucial for understanding the information density in the boundary theory. The paper begins by introducing the holographic hypothesis, which posits that a macroscopic region of space can be described by a boundary theory living on its boundary. The authors then discuss the specific case of Type IIB string theory on AdS5 × S5, which is dual to a 3+1-dimensional U(N) super Yang-Mills theory. They explain how correlation functions in the boundary theory can be expressed in terms of calculations in the bulk. The authors delve into the geometry of AdS space, representing it as a product of a unit four-dimensional spatial ball and an infinite time axis. They derive the relationship between the radius of the AdS space and the size of the gauge group in the boundary theory. They also discuss the IR-UV connection, showing how regulating the boundary area in the bulk theory is equivalent to regulating the UV cutoff in the boundary theory. In the third section, the authors make plausible assumptions about the information storage capacity of a cutoff field theory, leading to the conclusion that the number of degrees of freedom in the boundary theory is proportional to the area of the boundary. They further illustrate this connection by considering a thermal state of the boundary theory, which must represent an AdS Schwarzschild black hole. The paper concludes with general remarks on holography, discussing the nature of the mapping from the bulk to the boundary theory and the implications of the holographic principle in theories with a negative cosmological constant. The authors suggest that the holographic hypothesis may be sharpened for theories with zero or positive cosmological constant, but acknowledge the need for new ideas to address this case.