Why is North Korea test firing missiles?

The reason this is an important topic is because there potentially could be great danger and even the start of the war as a result of these missiles being fired. Who knows what these missiles could lead to, but it is important for the United States, and countries that are potentially in danger such as South Korea, to investigate and follow North Korean government very closely. This topic brings up the question of whether or not the war between North and South Korea is truly over. The shots from North Korea could also be either warning shots/threats from North Korea or actually preparing for a war to come.