The genitive is a grammatical case used to indicate possession or a relationship between nouns. In English, it is often formed by adding an apostrophe and "s" to a noun, such as in the phrase "John's book," which shows that the book belongs to John. The genitive can also be expressed using the preposition "of," as in "the cover of the book." In many languages, the genitive case has specific endings or forms that change based on the noun's gender, number, or case. For example, in Latin, the genitive form of "puella" (girl) is "puellae," indicating possession, such as "the girl's dress." Understanding the genitive helps clarify relationships between different elements in a sentence.