Short answers, pulled from the story.
Carbon is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent, meaning its atoms can form up to four covalent bonds, and it belongs to group 14 of the periodic table.
Carbon's abundance, its diversity of organic compounds, and its ability to form polymers at ordinary Earth temperatures make it the common element of all known life. It is the second most abundant element in the human body by mass, about 18.5 percent, after oxygen, and forms DNA, RNA, and ATP.
Carbon's allotropes include graphite, diamond, amorphous carbon, and fullerenes such as buckyballs and carbon nanotubes. Graphite is one of the softest known materials and conducts electricity, while diamond is the hardest naturally occurring substance and an electrical insulator.
Carbon-14 is a naturally occurring radioisotope created when cosmic rays interact with nitrogen in the upper atmosphere, and it decays with a half-life of 5,700 years. The amount stays nearly constant in living organisms but decreases predictably after death, a principle used in radiocarbon dating, invented in 1949, to date materials up to about 40,000 years old.
Antoine Lavoisier showed in 1772 that diamonds are a form of carbon when he burned charcoal and diamond samples and found that neither produced water and both released the same amount of carbon dioxide per gram. He listed carbon as an element in his 1789 textbook.
Carbon's nucleus forms inside giant and supergiant stars through the triple-alpha process, a nearly simultaneous collision of three helium nuclei at temperatures over 100 megakelvins. No significant carbon was created during the Big Bang, and most scholars hold that all the carbon in the Solar System and Milky Way comes from dying stars.
World production of natural graphite was 1.1 million tonnes in 2010, led by China with 800,000 tonnes, followed by India, Brazil, North Korea, and Canada. Diamonds were historically led by India and then Brazil, with primary deposits opening in the 1870s after South African fields were found, and Australia's Argyle mine producing 14 million carats in 2018.