* pH Scale: The pH scale measures the acidity or alkalinity of a solution. A lower pH indicates a more acidic solution, while a higher pH indicates a more alkaline (basic) solution.

* Acids and Bases: Acids release hydrogen ions (H+) in solution, while bases release hydroxide ions (OH-) in solution.

* Neutralization: When an acid and a base react, they neutralize each other. The hydrogen ions from the acid combine with the hydroxide ions from the base to form water (H2O). This process consumes both H+ and OH- ions.

* Shifting the Balance: Since the addition of a base introduces hydroxide ions, it will react with the hydrogen ions present in the acidic solution. This removes hydrogen ions, decreasing the acidity and thus increasing the pH.

Example: If you add baking soda (a base) to vinegar (an acid), the solution will become less acidic and its pH will rise.