What substances are called indicators, how do they affect acids?

Indicators are compounds that change color in a solution with different indicators of an acid-base medium. In order to determine what kind of reaction of the medium in the solution, different types of indicators are used. To determine the pH of the medium, acid-base indicators such as litmus, phenolphthalein, methyl orange are used.

The above indicators react to an acidic environment as follows:

Litmus in an acidic environment changes color and turns red.

Methyl orange also changes color in an acidic environment and turns pink.

Phenolphthalein in an acidic medium remains colorless.