An acid is any substance containing hydrogen that is able to donate one proton (hydrogen ion) to another substance. A base is a molecule or ion that can accept a hydrogen ion from an acid.
Acidic substances are often identified by their sour taste. Basically, an acid is a molecule that can generate H+ ion and can maintain favorable energy after loss of H+. Acids are known to make litmus blue red.
On the other hand, bases are characterized by a bitter taste and a slippery texture. A base that can be dissolved in water is called an alkali. When these substances react chemically with acids, they produce salts. The base is known to turn red litmus red.