A preposition is a word that tells you where or when something is in relation to something else. Examples of prepositions include words like 'after', 'before', 'on', 'under', 'inside' and 'outside'.

A suspiciously long prepositional phrase wasn`t the only irregularity that tipped a journalism grad student onto a mystery at Northwestern University. Mounted on a large rock on the Evanston campus, a ...