Last but not least is the notion of connectivity or a connected graph. In the next diagram, it is always possible to go from one vertex to another, whatever pair of vertices is considered. This graph is said to be connected. On the other side of the figure, you can see that D is isolated - there is no way to go from D to A, for example. This graph is disconnected, and we can even say that it has two components. We will cover the analysis of this kind of structure in Chapter 7, Community Detection and Similarity Measures. The following image shows connected versus disconnected graphs:
This is a non-exhaustive list of graph properties, but they are the main ones we will have to worry about within our graph database adventure. Some of them are important when creating the whiteboard graph model for our data, as we will discuss in the next section.
