A data structure is exactly what it sounds like — a structure that holds data. Unlike variables, which only hold a single point of data, data structures collect one or more points of data of the same type. Although a data structure can hold many points of data, a data structure, itself, is only a single object that can be stored in a variable like any other datatype. A data structure’s type becomes the type of the data points it holds. For that reason, a data structure is sometimes referred to as a container object, or a collection. Some data structures can expand infinitely in size, but others, like arrays have a fixed size.