Esters are produced by the yeast through the reaction between organic acids and alcohols produced during fermentation.
They are divided into:

• Higher esters → tropical fruits, citrus, apple, pear

• Lower esters → milder or spicier notes
  The amount and type of esters depend on:

• Yeast strain (Belgian, English, American…)

• Fermentation temperature and gravity

• Wort nutrients and oxygenation

They give the beer its fruity or floral character, complementing the malty and hoppy profile.