Here's why:

* Hydroxide ions (OH-): Bases release hydroxide ions (OH-) when dissolved in water. These ions are responsible for the characteristic properties of bases, like their ability to neutralize acids.

* pH above 7: The pH scale measures the acidity or alkalinity of a solution. A pH of 7 is neutral, values below 7 are acidic, and values above 7 are alkaline or basic.

* Forming hydroxide ions: When bases dissolve in water, they react with water molecules to produce hydroxide ions. This process increases the concentration of OH- ions in the solution, raising the pH.

Examples of bases:

* Sodium hydroxide (NaOH) - commonly known as lye.

* Calcium hydroxide (Ca(OH)2) - found in cement and used to adjust the pH of swimming pools.

* Ammonia (NH3) - a weak base used in cleaning products.

Important Note: While all bases produce hydroxide ions in water and have a pH above 7, the strength of the base varies. Strong bases completely ionize in water, producing a high concentration of hydroxide ions, while weak bases only partially ionize.