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The Laws of Thermodynamics are a bedrock of modern physics. Crucial to an understanding of the universe, these laws cut across all scientific disciplines. If you surf the web long enough you'll no doubt come across them quoted in one form or another. Knowing these laws will inform your understanding of both the physical world and everyday technology. 

1. Zeroth Law - "If two thermodynamic systems are in thermal equilibrium with a third, they are also in thermal equilibrium with each other." For example, if you have a hot cup of coffee, the cup will radiate heat until both the coffee and the surrounding air are at the same temperature, or thermal equilibrium.
2. First Law - "In any process, the total energy of the universe remains constant." Energy may change from one form to another, be passed between systems, but it cannot be created nor destroyed.

3. Second Law - "The entropy of an isolated system not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium." Put simply, everything degrades over time. Entropy is a measure of usable energy, and can be considered a measure of "chaos". The universe is moving from a state of structured order (stars, galaxies, atoms, metals) to a cold homogeneous soup, devoid of usable energy. See Heat Death.

4. Third Law - "As temperature approaches absolute zero, the entropy of a system approaches a constant." The Universe will attain absolute zero when all energy and matter is randomly distributed across space. The current temperature of empty space in the Universe is about 2.7 Kelvins.

Sources: 1, 2, 3, 4.