An adposition is a linguistic term that refers to a word or group of words that express a relationship between elements in a sentence, typically indicating location, direction, or time. Adpositions can be categorized into two main types: prepositions, which come before their objects (e.g., "in the park"), and postpositions, which follow their objects (e.g., "the park in"). Adpositions are essential in many languages, as they help clarify the connections between nouns and other parts of speech. They can also be combined with other words to form phrases, such as prepositional phrases (e.g., "under the table") that provide additional context in a sentence.