Popcorn is a variety of corn/maize kernel which expands and puffs up when heated.
Corn was domesticated about 10,000 years ago in what is now Mexico. Archaeologists discovered that people have known about popcorn for thousands of years. In Mexico, for example, remnants of popcorn have been found that date circa 3600 BC. Fossil evidence from Peru suggests that corn was popped as early as 4700 BC.
Air-popped popcorn is naturally high in dietary fibre and antioxidants, low in calories and fat, and free of sugar and sodium. This can make it an attractive snack to people with dietary restrictions on the intake of calories, fat or sodium. For the sake of flavour, however, large amounts of fat, sugar, and sodium are often added to prepared popcorn, which can quickly convert it to a very poor choice for those on restricted diets.
In a pan on the hob with a lid, heat a tbsp of oil, with a cup of kernels. Holding the lid on, shake to coat the kernels. Once the kernels start popping hold the lid and continue to shake periodically until the popping has stopped. Add flavourings, if required, while still warm; salt/melted butter/nutritional yeast/melted caramel.
Alternatively use a popcorn maker.