Universals are concepts or properties that can be attributed to multiple particular things or instances. For example, the color red can be seen in various objects like apples, fire trucks, and stop signs. In philosophy, universals are often discussed in relation to the debate between realism and nominalism, which concerns whether these properties exist independently of the objects they describe. In linguistics, universals refer to features or rules that are common across all human languages. For instance, most languages have a way to form questions, indicating a universal trait of human communication. These linguistic universals help researchers understand the underlying structures that shape language development and usage worldwide.