That's a fairly general question. In general, there are 3 types of circuits.
- Open Circuit
- Closed Circuit
- Complete Circuit
- Short Circuit
An open circuit is any series of electronic components where a path can not be draw from the power source through components and back. These do nothing.
A complete circuit is a where a path can be drawn from the source, through components, and back again. Generally speaking these are good.
You're interested in the short circuit, which is a type of closed circuit with no load. In short, no pun intended, there is a path from the positive voltage terminal back to the negative with no inductive, capacitive, or resistive elements. These are almost always bad, and lead to an ungodly amount of current flow, thus heat, melting, and component failure.
Examples(assume all connections are specified):
-A battery with the negative terminal connected to one end of a resistor is an open circuit.
-A battery with one end of an inductor, capacitor, resistor, or any combination thereof connected to both terminals is a complete closed circuit. That is one resistor lead goes to the negative terminal, the other to the positive.
-A battery with a wire leading from one terminal to the other, or from any voltage potential to ground is a short circuit.
Depending on the complexity of the diagram, it may or may not be tricky to find shorts. You should scan you diagram and post it if you want more specific help.
**edit** Oops, someone beat me to it, lol.