The North Atlantic Treaty Organization (NATO) and the Warsaw Pact were two important Cold War organizations. Describe their purpose and function as they relate to the Cold War.

The United States and 11 other Western nations formed the North Atlantic Treaty Organization (NATO) in 1949 as a way of standing together against further Communist expansion around the globe. In response, the Soviet Union and the nations in Eastern Europe under its influence signed the Warsaw Pact, the Communist equivalent of NATO, in 1955. Both organizations aimed to create a coordinated defense in order to deter an enemy attack against any one of their member states, creating two opposition alliances that would face off against each other in the emerging Cold War.
NATO reflected an important change in US foreign policy after World War II, as the nation departed formally from a policy of isolationism and linked its national security and defense to that of its allies in Europe. From its original member states of Belgium, Britain, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, and the United States, NATO membership expanded during the Cold War era to include Greece and Turkey, West Germany, and Spain. While the Warsaw Pact was responding indirectly to NATO’s formation, its signers (including Albania, Bulgaria, Czechoslovakia, East Germany, Hungary, Poland, and Romania) were more directly motivated by the rearmament of West Germany and its inclusion in NATO in 1955.

NATO was formed in 1949 as a consequence of the realignment of Europe into eastern and western camps after World War II ended. Eastern European nations had become communist satellite states of the Soviet Union, behind what Winston Churchill called the “iron curtain.” Western European democracies and the United States responded by signing the North Atlantic Treaty, the charter for NATO. Its Article Five included a collective security commitment by all NATO members. They pledged to view any attack on a single NATO country as an attack on the entire alliance. NATO cemented the transatlantic partnership of Western Europe with the United States and ensured the U.S. would use the threat of its nuclear arsenal to deter, or prevent, the outbreak of a new war against Soviet Russia.
When West Germany was admitted into NATO in 1955 and promised to re-arm, the Soviet Union—which by then had become a nuclear weapons state—and the Eastern European countries in its sphere of influence responded by creating their own collective security agreement, the Warsaw Pact. Through the remaining decades of the Cold War, the two organizations geographically represented the tenuous balance of power (or, considering the nuclear threat, the balance of terror) by which Europe kept the peace.

Both NATO (the North Atlantic Treaty Organization) and the Warsaw Pact were collective security treaties created during the Cold War. Basically, if a country within one of these treaties was attacked, all member nations of that respective treaty would rise in its defense and declare war against the attacker.
NATO was formed in 1949 against the USSR in an effort to stop the spread of Communism. The USSR was gaining power at this time and was using its strong forces to capture satellite countries. Member nations of NATO would defend each other from the possibility of the USSR taking control of their country.
In 1955, the USSR and other Communist nations in Eastern Europe formed a rival alliance, the Warsaw Pact. The Warsaw Pact was a symbol of Soviet dominance in Eastern Europe. The USSR could use the pact as an excuse to keep Soviet troops in other Eastern European countries and keep a close eye on its satellite states.
The creation of these two alliances made it difficult for the US and USSR to directly attack one another as this would lead to another World War. Thus, the US and USSR could not engage in direct confrontation or a “hot” war and instead fought one another through proxy wars in Non-Aligned countries like Afghanistan and Vietnam.
Interestingly enough, these collective security treaties were what gave rise to terms like "first-world", "second world", and "third world" when describing countries. First world countries referred to NATO member nations, while second world countries referred to Warsaw Pact member nations. Third world countries, on the other hand, were not part of either treaty and thus often fell victim to proxy wars.

Both Nato and thee Warsaw pact were the collective defense and deterrence organizations from both "blocks" during the Cold War, Nato was formed as a defense organization by the United States and the countries of Western Europe to thwart the advances of communism both in the European continent and abroad, while the Warsaw pact was formed by the Soviet Union as a counter to the Western Capitalist powers both in Europe and around the world.
Both organizations were charged with similar goals, albeit being ideologically opposed, as both acted as deterrent against the other succesfully creating a balance of power during the Cold war, coupled with Nuclear deterrence this collective security organizations served their purpose by keeping the war "Cold" instead of it going "hot", while they never had a direct confrontation agains one another they engaged in various proxy wars around the world succesfully shaping the International System during the second half of the 20th century.
One of the most important aspects of both NATO and the Warsaw Pact was the standarization of military procedure and equipment on their respective areas of influence, NATO on one hand modelled made the Allies adopt standard equipment, procedure and terminology on Europe, modeled of course after US military apparatus which meant that if the need arised the whole European and US military could mobilize in uniformity and coordination. The Warsaw pact on the other hand while not really standirizing the military as a coordination effort like NATO helped developing and modernizing the military apparatus of countries in the "Buffer Zone" as well as providing aid to other ideologically aligned governments, guerrillas, and movements around the world like the case of the Cuban Revolution were the rebels were armed and funded by the Warsaw pact or the case with "Las FARC" on Colombia were the guerrillas were trained, armed and funded by the Soviet Union.