A solution with a pH less than 7 is termed acidic. Acids are substances that donate protons (H⁺ ions) in a solution, directly affecting its pH level. The lower the pH, the stronger the acid, indicating a higher concentration of hydrogen ions. Acidity plays a crucial role in various chemical and biological processes, such as metabolism and the behavior of enzymes. Understanding acidic solutions is essential in fields like chemistry, biology, and environmental science, particularly in studies of soil and water quality.