R-trees are a type of data structure used for indexing multi-dimensional information, such as geographical coordinates or spatial data. They organize data in a hierarchical manner, allowing for efficient querying and retrieval of spatial objects. Each node in an R-tree contains a bounding box that encompasses its child nodes, which helps in quickly eliminating large areas of the search space. When searching for a specific object, R-trees use these bounding boxes to narrow down the potential matches, significantly speeding up the process. This makes R-trees particularly useful in applications like geographic information systems (GIS) and computer-aided design (CAD) where spatial data is prevalent.