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.

Agnes Caroline Thaarup Obel (born 28 October 1980 in Gentofte (north of Copenhagen) is a Danish singer/songwriter. Her first album, Philharmonics, was released by PIAS Recordings on 4 October 2010 in Denmark, Norway, Germany and other European countries. Since June 2011, Philharmonics is certified gold by the Belgian Entertainment Association (BEA) for sales of 10,000 units. At the Danish Music Awards in November 2011, Agnes Obel won five prizes for: Best Album Of The Year, Best Pop Release Of The Year, Best Debut Artist Of The Year, Best Female Artist Of The Year and Best Songwriter Of The Year.

Obel, and her younger brother Holger, grew up in an unconventional environment. Her father had three children from another marriage. He loved to collect strange objects and instruments like the xylophone and the double bass. Her mother, Katja Obel, was a jurist but also a brilliant musician. She used to play Bartók and Chopin on the piano. With a house full of sound and music : Agnes Obel learned piano at a very young age. During her childhood, Agnes Obel found inspiration in Jan Johansson's work. Johansson's songs, European folk tunes done in a jazzy style, have influenced the young musician a lot.

Avril Ramona Lavigne (pronunciation: /ˈævrɨl ləˈviːn/; AV-ril lə-VEEN; born 27 September 1984) is a Canadian singer-songwriter. She was born in Belleville, Ontario, but spent most of her youth in the small town of Napanee. By the age of 15, she had appeared on stage with Shania Twain; by 16, she had signed a two-album recording contract with Arista Records worth more than $2 million. In 2002, when she was 17 years old, Lavigne broke onto the music scene with her debut album Let Go.

Let Go made Lavigne the youngest female soloist to reach No. 1 in the UK, and the album was certified four-times platinum by the Recording Industry Association of America. By 2009, over 16 million copies had been sold worldwide. Her breakthrough single, "Complicated", peaked at No. 1 in many countries around the world, as did the album Let Go. Her second album, Under My Skin, was released in 2004 and was her first album to peak at No. 1 on the U.S. Billboard 200, eventually selling more than 10 million copies worldwide. The Best Damn Thing, Lavigne’s third album, was released in 2007, becoming her third No. 1 album in the UK Albums Chart and featuring her first U.S. Billboard Hot 100 No. 1 single, "Girlfriend". Lavigne has scored six number-one singles worldwide, including "Complicated", "Sk8er Boi", "I'm with You", "My Happy Ending", "Nobody's Home", and "Girlfriend". With more than 30 million copies of her albums sold worldwide, Lavigne is one of the top-selling artists releasing albums in the U.S., with over 10.25 million copies certified by the RIAA. Her fourth studio album, Goodbye Lullaby, was released in March 2011. Goodbye Lullaby gave Lavigne her fourth top 10 album on the U.S. Billboard 200 and the UK Albums Chart and her third No. 1 album in both Japan and Australia. Three months after the release of Goodbye Lullaby, Lavigne began work on her fifth album, which will be released on Epic Records following her departure from RCA Records.