Why bomb blast happening?

Bomb blast are happening all over the world specially in the Muslim world like Pakistan,Iraq,Afghanistan,Iran,Libya Why?Because in every one of these states the blast are happening due to saome reason.In Pakistan,its happening because the purpose is to spread fear among the people,by the terrorists.In Iran the same reason occurred.In Iraq,Afghanistan and Libya the purpose is to fight against the invaders who have attacked Libya,Afghanistan and Iraq.Bomb blast happen in every corner of the world & the major reason is to spread terror among the people & these terrorist dont want any person to stay happy & they are getting money aswell for such bad activities to make them happen. For some terrorist the purpose to make such bad activities happen is because of religion conflict.They want that people from different sect of a religion fight among each other & create terror.For some people the purpose is revenge,they want avenge by killing innocent people & military officials.they think by doing this they will get peace in their mind and for souls of their dead one would rest in peace.Some terrorist main purpose to make bomb blast happen in a country is that country shouldn't make progress economically & other country would stop investing in that specific country