This is very difficult because a volcano can appear very inactive but burst into life without warning. Scientists say that a volcano is active if it has erupted sometime during the last few hundred years. A dormant (sleeping) volcano is one that has not erupted for a few hundred years but has erupted during the last few thousand years. An extinct (dead) volcano is one that hasn't erupted for several thousand years and shows no signs of activity at all.
The lifetime of a volcano is measured in million years and people have trouble getting their heads around that sort of timescale. Volcanoes that have been dormant for thousands of years can be considered dead. If signs from the volcano tell scientists that an eruption might happen, some people don't believe it and they refuse to move from their homes to safety. Mount Pinatubo in the Philippines had been dormant for over 400 years before its eruption in 1991. Although people were warned, 740 were still killed and 8000 homes were destroyed.
The lifetime of a volcano is measured in million years and people have trouble getting their heads around that sort of timescale. Volcanoes that have been dormant for thousands of years can be considered dead. If signs from the volcano tell scientists that an eruption might happen, some people don't believe it and they refuse to move from their homes to safety. Mount Pinatubo in the Philippines had been dormant for over 400 years before its eruption in 1991. Although people were warned, 740 were still killed and 8000 homes were destroyed.