In the beginning, if a developer needed to store data then the way to do this was array based. There was nothing inherently wrong with arrays, except that you had to initialize them so they could only have a finite size, and trying to add past that size would result in something known as undefined behavior (meaning that just about anything could happen, though usually it would result in a crash). Eventually, it was possible to resize arrays, but this was difficult.

For anything more complex than a straight array, it was not a simple task. A linked list was possible (this can be considered as being a structure linked to another instance of the structure). The useful aspect of a linked list was that it was forever expandable and could be traversed up and down the list to find data. The downside was that the developer had to remember to clear the unused structures or risk running out of memory.