Monostable Operation of 555 Timer

Initially, the 555 timer has a lop output voltage at which it cal remain indefinitely.When the 555 timer receives a trigger at point A is time,the output voltage switches from low to high.The
output remains high for a while and the returns to the low state after a time delay of W.The output will remain in the low state until another trigger arrives.The duration of this output pulse can be precisely controlled with an external resistor and capacitor.