When an acid is dissolved in water, it produces hydrogen ions (H+). This is what gives acids their characteristic properties, like a sour taste and the ability to react with bases.

Here's a breakdown:

* Acids: Substances that donate hydrogen ions (H+) when dissolved in water.

* Hydrogen ions (H+): Positively charged ions that contribute to the acidity of a solution.

The more hydrogen ions an acid produces, the stronger the acid.

For example, when hydrochloric acid (HCl) is dissolved in water, it dissociates into hydrogen ions (H+) and chloride ions (Cl-):

HCl (aq) → H+ (aq) + Cl- (aq)

This process is called ionization or dissociation.