A word class that usually describes the relationship between words in a sentence. Prepositions can indicate:

• space (for example, ‘below’, ‘in’, ‘on’, ‘to’, ‘under’. 'She sat on the table.')

• time (for example, ‘after’, ‘before’, ‘since’. 'Í will go to the beach after lunch.')

• those that do not relate to space and time (for example, ‘of’, ‘besides’, ‘except’, ‘despite’, ’He ate all the beans except the purple ones').

Prepositions usually combine with a noun group/phrase to form a prepositional phrase (for example, ‘in the office’, ‘besides these two articles’).