„There are four general ways of storing information:
1. A list, in which one has a number of items, which may or not be related to one another. 2. A table, in which one has a number of items (records), each with a distinct set of properties or columns. 3. A tree, in which one has a hierarchy of items. 4. A graph, in which one has a number of items (nodes), with the nodes connected to each other in some way.“