The concept that through time and usage, new English words, definitions and grammars are being created.

Many grammarians have their favorite grammar pet peeves. Unfortunately, since English lives, some of the most heinous grammatical gaffes are now quite acceptable to the average speaker.

Example: prepositions require noun phrases. That is, you cannot correctly end a clause or sentence with a preposition.

    Where did you put the book at?
    should be written or said,
    Where did you put the book?
The habit was formed somewhere, and passed to children, and reinforced through repetition, until it has become so commonly used, that it is acceptable.