Quick answer
A short circuit is when live and neutral (or earth) accidentally touch, causing a huge surge of current. Protection comes from two things working together: the MCB that trips and cuts power instantly, and wire whose insulation can withstand the brief, intense heat of a fault without melting or igniting.
This is where the quality of the wire counts. Melt-resistant, e-beam cross-linked insulation such as APAR Anushakti Fire Protekt tolerates very high short-circuit temperatures, reducing fire risk during a fault. Always pair correctly-sized wire with a correctly-rated MCB — see how to choose the right cable.