The document discusses content-based image retrieval (CBIR). It defines CBIR as retrieving images from a collection based on automatically extracted features like color, texture, and shape. The document outlines the history and motivation for CBIR. It discusses features used for retrieval like color, texture, shape. Filtering algorithms and clustering methods used for CBIR are also summarized. Applications of CBIR include medical imaging, stock photography, and military intelligence. CBIR is presented as an effective alternative to text-based image retrieval.