The meaning of "security" is often treated as a common sense term that can be understood by "unacknowledged consensus". The content of international security has expanded over the years. Today it covers a variety of interconnected issues in the world that affect survival. It ranges from the traditional or conventional modes of military power, the causes and consequences of war between states, economic strength, to ethnic, religious and ideological conflicts, trade and economic conflicts, energy supplies, science and technology, food, as well as threats to human security and the stability of states from environmental degradation, infectious diseases, climate change and the activities of non-state actors.