The Ins and Outs of Prepositions

Prepositions pose more problems for the non-native speaker or learner of English than any other part of speech. Why? Prepositions are just little words that never change in form; they are pronounced softly, in unstressed syllables; they aren't even given capital letters in book titles; native speakers choose the correct ones without thinking. How can they be confusing?
The word "preposition" has a straightforward definition: a word placed before a noun or pronoun to define its relationship with another word in the sentence. For the learner of English, however, prepositions are anything but straightforward
Prepositions are difficult, if not impossible, to define without using other prepositions.