There are 3 ways to find a document. The primary method is a positional retrieval. This is achieved by keeping in mind where you left it. The next method is to identify the retrieval. You can retrieve by keep in mind its identity name. The last method is a relative retrieval. This is searching based on various features of the document.
For illustration, if you want to find a book on the Visual Programming, or a book containing the photographs of cricketers, the method must be relative retrieval. The positional and the identity retrieval also functions as the storage systems. If the retrieval system is based on the storage methods, then relative retrieval is not possible in this situation. The user will have to know where the content is stored and also by what name it is stored.