The following section will deal with the laws of separating foods and items from amongst other foods and items, such as separating cucumbers from tomatoes in a salad, or a white shirt from amongst other colored shirts. Doing so in certain cases involves the Borer/separating prohibition, as will be explained in this section. The general rule is the following: Any form of separating which is determined as a form of preparation for the food to be eaten, is forbidden to be done, while when done in the process of eating the food, is allowed to be done. The Sages defined which forms are considered a preparation and which are considered the form of eating.
The following section below will explain which mixtures are defined as actual mixtures and thus receive the separating restrictions which will be explained in Halachas 1-2. Any mixture which is not defined as a mixture in this regard does not contain any separating restrictions being that the pieces are already considered separated.