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. For example, the total energy consumption of the entire world in a year can be measured in exajoules, highlighting the scale of energy use in relation to renewable energy sources and fossil fuels.