Multilevel index

A multilevel index is a hierarchical way to organize and quickly locate data in large databases or files. Instead of searching through every record, it uses indexes—like bookmarks—that point to sections of the data. When the index itself gets large, a second-level index is created to point to the first, forming multiple levels. This approach reduces search time by narrowing down the search area step-by-step, making data retrieval efficient even with vast amounts of information.