What is a fuse wire? What is the advantage and disadvantage of using a thick fuse wire?

A fuse is a very important device used for protecting electric circuits. It is a wire made out of a metal like tin or tin alloy having a very low melting point. 

When a high current flows through a circuit, the fuse wire gets heated or melts due to short-circuiting or overloading. Hence the circuit is broken and the current stops flowing. This saves all the appliances of the circuit.