overview what sorts of problems can you solve with knowledge of these topicsas rough approximationwe might divide the situations in which they're useful into three categoriesreal-world data storage programmer' tools modeling these are not hard-and-fast categoriesbut they may help give you feeling for the usefulness of this book' subject matter let' look at them in more detail real-world data storage many of the structures and techniques we'll discuss are concerned with how to handle real-world data storage by real-world datawe mean data that describes physical entities external to the computer as some examplesa personnel record describes an actual human beingan inventory record describes an existing car part or grocery itemand financial transaction record describessayan actual check written to pay the electric bill non-computer example of real-world data storage is stack of -by- index cards these cards can be used for variety of purposes if each card holds person' nameaddressand phone numberthe result is an address book if each card holds the namelocationand value of household possessionthe result is home inventory of courseindex cards are not exactly state-of-the-art almost anything that was once done with index cards can now be done with computer suppose you want to update your old index-card system to computer program you might find yourself with questions like thesehow would you store the data in your computer' memorywould your method work for hundred file cardsa thousanda millionwould your method permit quick insertion of new cards and deletion of old oneswould it allow for fast searching for specified cardsuppose you wanted to arrange the cards in alphabetical order how would you sort themin this bookwe will be discussing data structures that might be used in ways similar to stack of index cards