Introduction, Preface & Foreword: plz explain

Because my higher education has been largely autodidactic, I have never been clear in my mind whether there are any distinctions between these designations. Are they interchangeable or are they wholly separate species?

Introduction is where the plot spoilers go.

intro is exactly what it sounds like. welcome to my book! boy, are you in for a treat. here's the scoop! preface is when you wanna impress people with how many books you read before you wrote your book and you wanna thank that one guy. foreword is the guy you got to say nice things about you.

One of my favourite writers, William H Gass, wrote a very funny essayabout the differences between these:

"In times past it was customary to load a book with more of these burdens than is the habit now. Normally we save introductions for reissues. A fancy edition of The Way of All Flesh may contain a frontal essay by Theodore Dreiser while a cheap ‘just for study’ copy will be hawked by a professor from the Virginia Polytechnic Institute. My treasured copy of Robert Burton’s Anatomy of Melancholy has a preface by F.D. & P.J.-S. and an introduction whose Part I is by P.J.-S. and whose Part II, briefer, is by F.D., which suggests these initials know the difference. This is followed by Burton’s poem, ‘The Argument of the Frontispiece’, next by the ‘Frontispiece’ itself and another poem, longer, which is an address by the author’s pseudonym, Democritus Junior, to his book – ‘Go forth, my book, into the open day.’ This done, space is made for still another set of verses titled ‘The Author’s Abstract of Melancholy’ with its famous refrain, ‘Naught so sweet as Melancholy’, when, hard upon, I shall encounter an introduction, ‘Democritus Junior to the Reader’, of 93 pages. Have we got to grandmother’s house yet? No. We now turn a leaf headed ‘To the Mischievously Idle Reader’, written in both prose and verse, and subsequently find the four-page synopsis of the Anatomy’s ‘First Partition’ laid out like a densely ploughed field."

harlan ellison to thread.

http://covers.powells.com/9780521413503.jpg

someone should write a 300-page introduction to a five page book of poems. one poem per page. all haikus. you can use the intro to explain your poetic motivations.