A mixture is a combination of two or more substances that are not chemically bonded. Each substance in a mixture retains its own properties, meaning they can be separated by physical methods. Common examples of mixtures include salad, sand and salt, and air, which contains various gases. Mixtures can be classified into two main types: homogeneous and heterogeneous. A homogeneous mixture has a uniform composition throughout, like saltwater, while a heterogeneous mixture has distinct, separate components, such as oil and water. Understanding mixtures is essential in fields like chemistry and cooking.