Style can described as mode of expression in
language. Style is more than that for there are
style guides which purport to help us write
grammatically acceptable prose.
The above link will take you to a well known online
bookseller. Bartleby provides online links to The
Element of Style by William Strunk Jr.
Jack Lynch offers an index of the elements of
English in common contemporary usage. His
comments and explanation of the choice of the
indefinite article, a or an being subject to sound
rather than to the letter is something that is not
being taught in our schools.