The document provides a comprehensive review of learning techniques in content-based image retrieval (CBIR), focusing on relevance feedback (RF) methods that help bridge the semantic gap between low-level extracted features and high-level user expectations. It categorizes various short-term and long-term learning approaches, discusses state-of-the-art techniques, and highlights challenges such as capturing semantics and the high dimensionality of image features. The paper also details the architecture of CBIR systems and examines different similarity measures and feedback mechanisms to enhance retrieval effectiveness.