Acids and bases are two important types of substances in chemistry. Acids, like lemon juice and vinegar, have a sour taste and can turn litmus paper red. They release hydrogen ions (H⁺) when dissolved in water, which makes solutions acidic. Common examples include hydrochloric acid found in our stomachs and citric acid in fruits. On the other hand, bases, such as baking soda and soap, taste bitter and feel slippery. They turn litmus paper blue and release hydroxide ions (OH⁻) in water, making solutions basic or alkaline. Everyday examples include sodium hydroxide used in cleaning products and ammonia found in some household cleaners.