A node is anything when seen as part of a larger system. As a knowledge explorer, when you create artifacts you will usually be thinking of them as elements in something larger. In the opening stages of any inquiry, the first order of business is to generate as many artifacts—nodes—as possible, so you want to begin from as wide an angle as possible. We call this kind of exercise node generation.
One method for generating nodes is called the Post-Up (see a full description in Chapter 4). To post up, you begin with some kind of fire-starter to set the parameters that define your list. To start with a simple example, imagine that you are going shopping and need to create a list of groceries. You could start with a simple question: "What do I need from the store?" Instead of a typical brainstorming session, where people call out ideas and a facilitator makes a list that everyone can see, you ask people to generate their ideas silently, using sticky notes—one idea per note.
Doing this accomplishes two goals. First, since it's an opening exercise, you will get a more diverse set of ideas by asking people to generate them silently. Second, by asking people to write each idea on a separate sticky note, you are generating a set of modular, movable artifacts that you will later be able to shuffle, sort, and reorganize.
When people are finished generating ideas, ask them to take turns going up to a flip chart or whiteboard and sharing their ideas with the group, as follows: read each sticky note aloud and place it on the board where everyone can see it. Notice that this Post-Up process is a version of break out/report back. The breakout begins when you ask people to start writing ideas, and the report back ends when everyone has finished sharing ideas and the board is filled with sticky notes.