record often represents real-world objectsuch as an employee or car part record is divided into fields each field stores one characteristic of the object described by the record key is field in record that' used to carry out some operation on the data for examplepersonnel records might be sorted by lastname field database can be searched for all records whose key field has certain value this value is called search key the array workshop applet suppose that you're coaching kids-league baseball team and you want to keep track of which players are present at the practice field what you need is an attendancemonitoring program for your laptopa program that maintains database of the players who have shown up for practice you can use simple data structure to hold this data there are several actions you would like to be able to performinsert player into the data structure when the player arrives at the field check to see if particular player is present by searching for his or her number in the structure delete player from the data structure when the player goes home these three operations will be the fundamental ones in most of the data storage structures we'll study in this book in this book we'll often begin the discussion of particular data structure by demonstrating it with workshop applet this will give you feeling for what the structure and its algorithms dobefore we launch into detailed discussion and demonstrate actual example code the workshop applet called array shows how an array can be used to implement insertionsearchingand deletion start up this appletas described in appendix awith :appletviewer array html figure shows what you'll see there' an array with elements of which have data items in them you can think of these items as representing your baseball players imagine that each player has been issued team shirt with the player' number on the back to make things visually interestingthe shirts come in wide variety of colors you can see each player' number and shirt color in the array