Nodes are containers for ideas about your data and can be seen as representing the themes or categories that emerge from your Sources. We liken nodes to files held within a suspension filing cabinet – as a theme emerges from our data, we take that ‘chunk’ or ‘scoop’ of material/s and place it in one of our ‘files’ that has been appropriately named for the theme we are coding. Later, these nodes can be used to ask questions of our data, and importantly, we can also store the results of the questions we have asked, i.e. the interrogations of the data we have completed, as nodes.

Your project can have as many nodes as necessary (watch, however, that your overall number of nodes is not too large) and can be organised into a hierarchy or, if you prefer, need not be organised at all. As nodes are highly flexible you can create nodes at any time and you can alter the way you have organised them as you rethink your ideas. Depending upon your methodology, you may choose to create your nodes at the beginning of your project and place your coding into nodes later, or you may elect to create them as you perform the coding itself (or indeed, a combination of the two!). 

Nodes represent more than just themes though - NVivo 9 has three different types of nodes which are described below:

• Nodes: Nodes are containers for your themes, people, places, organisations or other areas of interest. You can organise these nodes in hierarchies - moving from general topics at the top (the 'parent' node) to more specific topics ('child' nodes). If there is no logical connection between your nodes (or perhaps these connections are not yet apparent) you can just add nodes at the top level of the hierarchy. Note that nodes are now a more general area to store what used to be termed 'free nodes', 'tree nodes' and 'cases' in earlier versions of the software.
• Relationships: A node that defines the connection between two project items. For example, the relationship between nodes (Poverty impacts Health).
• Matrices: A collection of nodes resulting from a Matrix Coding Query.