In a broad sense, nearly all problems can be thought of as search problems. If we can define the space of possible solutions, we can search that space to find a correct solution. For example, to solve the pegboard puzzle (Exploration 5.2) we enumerate all possible sequences of moves and search that space to find a winning sequence. For most interesting problems, however, the search space is far too large to search through all possible solutions.
This section explores a few specific types of search problems. First, we consider the simple problem of finding an element in a list that satisfies some property. Then, we consider searching for an item in sorted data. Finally, we consider the more specific problem of efficiently searching for documents (such as web pages) that contain some target word.