3 - Data Structures GapFill

A data structure is a means by which data is stored in an organised way. While variables are sometimes described as data structures, the term tends to apply to a single structure that can store multiple data items.  StacksListsArraysQueues are one such data structure, in which a fixed number of spaces, called  elementspigeonholesreferencesboxes, are created  when the data structure is initialisedwhen the containing subroutine is calledwhen the application begins executionbefore the data structure is initialised. Each one of these spaces is addressable via its  referencepointerstubindex, the first being  10-1n and the last being  n-1n-1n+1.  ListsStacksQueuesArrays are an example of a last-in-first-out data structure, in which only the most recently added data item is accessible. Data items can be  pushedpulledpoppedpeeked onto the structure or  pushedpulledpoppedplaced from it, the latter of which entails removing it. A related data structure is the  listqueuearraystack, which is an example of a first-in-first-out data structure.  QueuesArraysTreesStacks are a specific type of  arraygraphstackqueue, in which each item of data points to other pieces of data. This is a non-linear, hierarchical data structure, with the  rootbasebranchleaf conceptually at the top.