Prepositions are words that show the relationship between a noun and something else in a sentence. Words like 'on', 'under' and 'inside', as well as phrases like 'next to', 'in front of', and 'on top ...
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'.