Node labels

Node labels are a way of semantically categorizing the nodes in your graph. A node can have zero, one, or more labels assigned to it--similar to how you would use labels in something like your Gmail inbox. Labels are essentially a set-oriented concept in a graph structure: they allow you to easily and efficiently create subgraphs in your database, which can be useful for many different purposes, such as querying on only a part of your database content. One of the most important things that you can do with labels is create some kind of typing structure or schema in your database without having to do this yourself (which is what people used to do all the time before the advent of labels in Neo4j 2.0). A node with one label is comparable to a row in a table. There is no comparison with the (so-called) relational world for a node with several labels. Although not required, a node should have at least one label.