Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air. Other processes used to convert fuel into energy include various other exothermic chemical reactions and nuclear reactions, such as nuclear fission or nuclear fusion. Fuels are also used in the cells of organisms in a process known as cellular respiration, where organic molecules are oxidized to release usable energy. Hydrocarbons are by far the most common source of fuel used by humans, but many other substances, such as radioactive metals, are currently used as well .

Chemical fuels are substances that release energy by reacting with substances around them, most notably by the process of oxidation.

Biofuel can be broadly defined as solid, liquid, or gas fuel consisting of, or derived from biomass. Biomass can also be used directly for heating or power—known as biomass fuel. Biofuel can be produced from any carbon source that can be replenished rapidly e.g. plants. Many different plants and plant-derived materials are used for biofuel manufacture.

Nguyễn Tuân (May 10, 1910 - July 28, 1987) was a renowned Vietnamese author. Current literature books for public school in Vietnam rank him as one of the nine biggest authors of contemporary Vietnamese literature. He is known for his essays on multiple subjects, with a clever and creative way in using the language. Hanoi has a street named after him, that street is in Thanh Xuan district.

Nguyễn Tuân was born and raised at the village Nhân Mục, Thượng Đình, which is now the neighborhood Nhân Chính, district Thanh Xuân, Hanoi, Vietnam. His family was the traditional Confucianists, but by the time of his childhood, Confucianism and the traditional Chinese-influenced education had started to decline, replaced by the more modern French-influenced culture.

In 1929, during his last year of the intermediate schooling (the equivalence of ninth grade in junior high school), Nguyễn Tuân was suspended because of his participation in a petition against a few French teachers, who demeaned Vietnamese people. Shortly after, he was imprisoned for illegal crossing the border of the colonial French Indochina to Thailand. Upon his release, he started writing as a journalist and a writer.