The effects of short circuits:
A short circuit is a path for current where a path should not exist, the path is generally considered to have a low resistance. If a short circuit is placed across a resistor, the current will flow through the short circuit rather than through the resistor.
Short circuits across series or parallel connected resistors will result in a decrease in the circuit resistance and an increase in the current drawn from the supply. Short circuits may result in the fuse blowing, the circuit breaker tripping or the circuit burning out if no protection devices are fitted.
If the definition of a short circuit is taken to be 'an unwanted current path', then high resistance short circuits are also possible.