This paper provides an overview of rate-distortion (R-D) optimization techniques and their practical application in image and video coding. It begins with a discussion of classical R-D theory, highlighting the fundamental performance bounds on compression systems. The authors then explore how R-D can be applied in practical coding scenarios, such as standards-compliant environments, and introduce two popular techniques for resource allocation: Lagrangian optimization and dynamic programming. The paper also reviews recent literature in these areas, citing applications related to image and video compression and transmission. Key points include the importance of choosing appropriate models for complex sources like images and videos, the role of transform coding in achieving good compression performance, and the challenges of delay-constrained transmission and buffer control in video compression. The paper emphasizes the practical significance of R-D techniques in improving compression efficiency and quality, particularly in standards-based video coding.This paper provides an overview of rate-distortion (R-D) optimization techniques and their practical application in image and video coding. It begins with a discussion of classical R-D theory, highlighting the fundamental performance bounds on compression systems. The authors then explore how R-D can be applied in practical coding scenarios, such as standards-compliant environments, and introduce two popular techniques for resource allocation: Lagrangian optimization and dynamic programming. The paper also reviews recent literature in these areas, citing applications related to image and video compression and transmission. Key points include the importance of choosing appropriate models for complex sources like images and videos, the role of transform coding in achieving good compression performance, and the challenges of delay-constrained transmission and buffer control in video compression. The paper emphasizes the practical significance of R-D techniques in improving compression efficiency and quality, particularly in standards-based video coding.