Electrically, a node is any continuous
section of a circuit
sharing the same voltage
. Typically this occurs at the junction
of different component
s, but a node is not
just the junction.
See also node analysis.
As an extra thought: Since any number of components can be connected to a node, it can used as a method for locating components. If one names each node, and then indicates, for each component, which terminals of the component connect to which nodes, one has an unambiguous mapping of a circuit; this is, for example, the approach that spice uses.