patterns that occur universally across natural languages, such as properties that all human languages share or implications about the relation between the occurrence of one feature and the other
Linguistic universals are those properties which are shared by all languages, or statements which are true of all languages. For example:
All languages have vowels.
All languages have pronouns.
There are also implicational universals, in which one feature is universally correlated with another, for example:
If a language has trial pronouns then it also has dual pronouns.
The study of linguistic universals is closely allied to linguistic typology.