## TL;DR
The Cold War defined global politics for 45 years — an ideological struggle between capitalism and communism, enforced by nuclear deterrence and fought through proxies, propaganda, and technological competition.

## Core Explanation
Origins: ideological incompatibility (Marxism-Leninism vs. liberal democracy), power vacuum after WWII, Soviet expansion in Eastern Europe, US containment policy (Truman Doctrine, Marshall Plan). NATO (1949) vs. Warsaw Pact (1955) institutionalized the divide.

## Detailed Analysis
The nuclear arms race: Mutual Assured Destruction (MAD) paradoxically maintained peace through the certainty of total annihilation. Space race: Sputnik (1957, USSR) → Apollo 11 moon landing (1969, USA). Détente (1970s), renewed tensions (Reagan era), Gorbachev reforms (glasnost, perestroika), fall of Berlin Wall (1989), Soviet dissolution (1991).

## Further Reading
- Cold War International History Project
- National Security Archive
- CNN Cold War Documentary Series