Search refers to the ability of finding any number of items of information with specified properties within a collection of similar items (items sharing the same type of properties).
Search functionality is implemented through search algorithms. A search algorithm is capable of reading a collection of items and returning only those that satisfy a condition.
Any type of item that can be described through by one or more properties can be searchable. Text, images, files, folders, objects, websites, web pages, all are examples of commonly searchable items.
For more information, see Search Algorithm.