Everyone?

Was the Cold War a Third World War?
The Cold War was a period beginning about 1948 which resumed the pre-1939 hostility between the Soviet Union and the western powers. That is, the temporary alliance from 1942 to 1945 for the purpose of defeating Hitler ended.
The Yalta agreement seemed to assume that the Soviet occupation of east and central Europe was to be temporary while elections could be organized. Roosevelt appears to have refused to admit the real character of Stalin, though he was warned by Churchill. When the elections took place they were usually of the same kind as in the Soviet Union, except for Czechoslovakia where Communists won a large part of Parliament but not a majority.

The Cold War is said to have begun when the Communists in Czechoslovakia staged a coup and ejected the non-Communist President and Prime Minister. Other signs of Stalin's hostility were: his refusal to accept American Marshall Aid both for the Soviet Union and eastern Europe; Stalin's attempts to drive the other allies out of Berlin by blockading the land and water routes from western Germany. This resulted in the Berlin airlift and later the formation of a west German Republic, and then the formation of the North Atlantic Treaty Organization (NATO).

The Korean War and Vietnam war were perhaps parts of this war.
However, the Cold War was mainly a user of materials in building weapons which were not used directly by the Great Powers. These produced a general atmosphere of terror of nuclear war - and perhaps also very rapid technical development. Otherwise a large number of "small" wars, mostly in the former colonial territories took place: Angola, Mozambique, Congo, Chad, Guatemala, Cuba, as well as the wars in the Middle East. Afghanistan was perhaps one of the "small" wars (actually it was a major war for the Afghans).

There was a hidden war of secret agents and covert operations, each side organizing coups and client governments in the former colonial countries.

Was it a war between Socialism and the Free market (capitalism)? or was it mainly about national power? Historians will argue about this, probably for generations. Indeed, already the view is being expressed that the Soviet Union was never in fact a threat to the west, as on its collapse Russia and its other states was revealed as a third world economy. In this case the Cold War was perhaps a kind of fraud with the purpose of accelerating technical developments.

New World War?
Is there a third world war going on now?

In the 1990s the wars in Yugoslavia and parts of the former Soviet Union: Chechnya, Tajikistan, Georgia, Azerbaijan, Armenia, suggested there was a danger of worldwide instability. However, most of these wars have died down.

There are still some legacies of the former Cold War. The two Koreas remain a source of potential fighting, especially as South Korea is a successful modern economy while the North is a primitive autocracy - with nuclear weapons. The dispute between Cuba and the United States continues, at least until Fidel Castro dies.

Many Muslims are hostile to the western dominated world, and especially to support for Israel by the United States. This has led to the Taliban in Afghanistan and their association with Osama bin Laden, provoking individual acts of terrorism in western cities, and in their third world allies, such as Kenya and Tanzania.

A major war in the Congo, mainly about control of raw materials, has killed millions.

The threatened shortage of fossil fuels, especially oil and gas, has led to tensions between the various consumers, especially the new economy of China, and may already have sparked a war in Darfur, Sudan. As much of the remaining oil is in Muslim countries this rivalry exacerbates disputes with the Muslim world.

Terrorism
Is there a new terrorist war? See the section on Non-government wars. What are the causes of Muslim alienation? Clearly a major one is western support for Israel. Another is the weak pro-western governments whose main purpose is to keep western access to the oil.

Oil
Perhaps the greatest threat comes from the need for raw materials, especially oil. China and India's consumption of oil is growing at a rapid rate, but oil extraction may already have reached its maximum - see peakoil. The war in Darfur Sudan has already been attributed to a scramble for oil between China and the United States, and the war in Iraq seems to have something to do with Iraq's huge oil reserves.

Russia's power is reviving as it uses the supply of gas to its neighbors, including former members of the USSR and western Europe, to exert political power.

Outlook
Perhaps a war of the kind experienced in the 1940s is not very likely - huge armies on the move; millions dying in bombardments. Nor is the nuclear holocaust people feared at the height of the Cold War and Mutually Assured Destruction - even if there are people who should know better proposing the use of nuclear weapons. But peace of the kind supposed to have occurred during the height of the western hegemony is not very likely either. And in the third world? Countries like the Congo seem doomed to endless war forever. Also the Middle East.

An even greater danger would seem to be the breakdown of civil society caused by the immense destructive ability of modern weapons. Destruction is easy and cheap; rebuilding is long and difficult. Iraq is a good example. Lebanon after the Israeli attacks of 2006 is another. Societies without government may be increasing. Climate Change is certain to produce huge instabilities.