pH measures the number of hydrogen ions in a solution and it tells us whether a solution is an acid or a base. The pH scale ranges from 0 to 14. Any solution that has a pH from 1 to 6 is acidic, any solution with a pH value of 7 is neutral and any solution with a pH value between 8 to 14 is basic. Following are the applications of pH :Animals and other living beings need a certain pH to live. For example, all the physiological activities in the human body generally take place within the values of 7 and 7.8. When the value of water increases due to acid rain and the addition of pollutants, aquatic life is threatened as the change in pH value depletes their environment.pH value is important for the proper digestion of food in our stomach. The stomach releases hydrochloric acid with a pH value of 1 to 3 which helps in digesting food and converting it into energy. The food we consume and the bacteria present in our mouth reduces the pH value. To counter this acidic activity we use toothpaste and tooth powders that are basic. It protects our teeth from tooth decay and other oral problems. Some animals like ants and honeybees sting us and cause us pain. The acid they release into our body is acidic and to counter the pain, medicines with neutral pH value or basic are used to reduce the pain.