What are function words?
Proponents of the structural approach to grammar make a useful distinction between words which have a lexical meaning (nouns, verbs, adjectives, adverbs) and those which merely show relationship or degree (determiners, qualifiers, auxiliaries, prepositions, etc.) The latter are called function words. Few of them show any formal features that permit positive structural identification, but it is possible in the case of some to indicate the positions in which they are most likely to occur.
Please follow the links for an explanation of function words and the position where they are placed: