An exajoule (EJ) is a unit of energy in the International System of Units (SI). It is equal to 10^18 joules, which is a very large amount of energy. To put it in perspective, one exajoule is roughly equivalent to the energy produced by burning about 25 billion liters of gasoline. Exajoules are often used in discussions about global energy consumption and production, especially in relation to large-scale energy sources like solar power, nuclear energy, and fossil fuels. Understanding exajoules helps in analyzing energy trends and making comparisons between different energy systems.