Biochar is a carbon-rich material created through the process of pyrolysis, which involves decomposing organic materials at high temperatures in an oxygen-limited environment. It enhances soil fertility and retains significant amounts of carbon, offering benefits for carbon sequestration and agriculture, including increased crop yields and reduced fertilizer runoff. The document outlines the creation of biochar, its advantages, and its historical context related to terra preta, emphasizing its potential in sustainable farming practices.