What is the role of a fuse used in series with any electrical appliance? Why should a fuse with a defined rating not be replaced by one with a larger rating?

(N/A) fuse is a safety device used to protect electrical appliances from damage caused by short-circuiting or overloading.
It is designed to carry a specific maximum current. When the current flowing through the circuit exceeds this rated value,the fuse wire melts and breaks the circuit,thereby preventing damage to the appliance.
If a fuse with a larger rating is used,it will not melt even when the current exceeds the safe limit of the appliance.
Consequently,the appliance may get damaged or catch fire because the protective mechanism fails to operate. Therefore,one should always use a fuse of the correct rating.