|Resistors in series
|Resistors in parallel
|Potential divider 1
|Potential divider 2
A potential divider is a simple circuit with multiple resistors in series, where the voltage across the resistors is split proportional to the resistance.
A circuit with nested series or parallel parts to it can be simplified "from inside out", much like evaluating brackets in a mathematical expression.
An open circuit is a circuit with an infinite resistance load connected to the power supply - which, in practice, means that the terminals of the power supply are not connnected.
A short circuit is the opposite of an open circuit - it's where there the terminals of the power supply are connected with no resistance. In practice, this usually means the terminals are connected by a wire or other conductive material with negligible resistance.