You can thank me, beat me, or march on my castle with an army of angry peasants, later.
THE LIFE STAGES OF A BOOK: FROM PAGE TO PUBLICATION.
Stage I: The Larva (IE, "The Manuscript.")
We're picking up with the assumption that the book has already been written, approved by your agent/primary beta reader, and sold to a publishing house (or, if you prefer, your frickens have already done the nasty in the romantic swamp setting of their choosing, and have laid the fertilized eggs in a suitable pool of semi-stagnant water). Now, your manuscript gets to go into something called "editorial review." Different houses and different editors will have different names for this process; when I'm doing it to myself, I tend to call it things like "why God why" and "getting blood on the ceiling." This is the stage where you'll actually have some input, and can even argue.
Some manuscripts sail the waters of editorial review with nary a ripple. Others will be shredded and stapled back together several times before they're allowed to take the next step forward. Whatever the case happens to be with your manuscript, assume that it's going to take some time, and just keep breathing.
Stage II: The Hatchling (IE, "Copy-editing.")
So you've made all the changes your editor requested and returned an approved manuscript to your publishing house. Awesome. Your beloved baby book has emerged from its gooey amphibian egg and is now thrashing around the puddle, downy feathers all plastered down and making it swim more slowly, thus becoming an easier target for predators. In this case, the predator is someone with a red pen and an eye for typos. Your manuscript will take some time to review, because they're trying to be thorough; a book pushed out of the puddle before it has time to mature is probably going to get punctuation all over the floor.
You may or may not ever see your copy-edited manuscript. I have a clause in my contract that lets me see mine, because I'm neurotic that way. Lilly appreciates this clause, because she likes to sleep on manuscripts. I, also, appreciate it, because every typo that slips past me is a dagger in my soul, and I try to remain as un-stabbed as possible.
Stage III: Adolescence (IE, "Page Proofs and ARCs.")
Once your copy-edits have been made, two things will happen at basically the same time. Think of them as your weird little tadpole starting to sprout legs and flight feathers at the same time. The poor guy is all over the place, and both flying and swimming are out of the question until he figures out which direction is "up."
Your page proofs are basically a bunch of loose pages comprising your entire copy-edited book. As the author, you will generally get the opportunity to go through them and catch any little things that might have been missed earlier in the process. Note the stress on "little." The idea is not to rip out that chapter you've always hated; it's to catch that three-word continuity error on page seventeen, and that slightly out-of-synch tense on page eighty-four. By the time a book reaches proofs, it should be essentially ready to go. The ARCs, on the other hand, are your Advance Review/Reader Copies. These will be bound editions of the manuscript, potentially with covers, probably with any blurbs you've managed to collect, sent out to reviewers, trade publications, and major genre bookstores about four to six months before publication.
Stage IV: Frog (IE, "Publication.")
After your page proofs have been returned and your ARCs have been sent out, your book will go to press, and your weird-ass feathered frog will hop free of the puddle it was born in for the first time. Printing and shipping will take however long your publisher thinks it should; you can make sure there are no delays on your end by turning in your proofs by the deadline. You should have a publication date. Cling to it as best you can.
Watch your feathery amphibian creation fly.