Prepositions are words which express relationships between two items. Primarily they express location (position) and come before a noun (pre-). E.g.,The bottle is on the table, in the cupboard, etc. They are also used to express time relationship: on Wednesday, at 4.O clock, in August. These words are also used in more abstract ways: interested in, look forward to, the study of.

There is a high number of prepositions in English, and they are difficult for learners to master.