Pre-orders are when you buy a book before the release date. Some publishers and authors offer incentives to pre-order. It may be cheaper to pre-order as well. Sometimes though it isn't so you have to be okay with paying a higher price.
I have a love/hate relationship with pre-orders.
What is there to love?
I never miss a new release in a series that I am reading or by a favorite author. If I stress about missing a date for a new release and have pre-ordered it tells me that I am safe, when I click on the book. I read a lot on my kindle and pre-ordering means that when I wake up in the morning or get home from work there is a forgotten present waiting for me to open. Who doesn't like presents?
What is there to hate?
When pre-orders happen closely to each other or even on the same day, you have to choose which one to read first. This may stress me out, opening one book before the other may seem like I like that story/author better. I realize that no one else knows which one I opened first but I know. Then I have to justify it to myself. If I am in the middle of a book and the pre-order comes in, I may accidentally forget to read it later on. Even if it was a highly anticipated, oh my goodness no the the author did not just end it like that cliffhanger. As in right now, I have four books from the beginning of the year that I still haven't read from my most anticipated list. I have them, I can open them, I could read them but the release date for the next one is still six months out...
So there you have it...readers guilt or peace of mind?
Peace of mind always wins. Pre-orders happen around here on a fairly consistent bases. I love them, yet there is some resentment there.