An acidic solution is a liquid that has a pH level less than 7. This means it has a higher concentration of hydrogen ions (H+) compared to hydroxide ions (OH-). Common examples of acidic solutions include vinegar, which contains acetic acid, and lemon juice, which contains citric acid. Acids can be classified as strong or weak based on their ability to dissociate in water. Strong acids, like hydrochloric acid (HCl), completely dissociate, while weak acids, like carbonic acid (H2CO3), only partially dissociate. Acidic solutions play important roles in various chemical reactions and biological processes.