Many book sellers on Ebay will use in the title or sub title of their listing the phrase "1st edition". Do they really have a first edition book? To answer this question, one has to understand what it takes to be a true first edition book.
In my opinion the term "first edition" is the most misused term on Ebay. I really wish that Ebay would ban it's use. The term should be replaced with "first printing", which is really what a first edition book is. Many books will say first edition on the copyright page, but will no longer be in the first printing. This is because the publisher will just leave the term there through all the subsequent printings of a book. A good example of this happened last year with the book "The Audacity of Hope" by President Barack Obama. Many sellers were claiming to have a first edition of the book, and asking highly inflated prices for it. When asked what number printing the book was, they sheepishly had to reply "oh...the 29th". This is because the pulisher had left the term, first edition, on the copyright page through all of the book's printings. Keep in mind that this book sold out of it's first printing very quickly, and the publisher had to rush to get new printings out the door. I had to wait several weeks to get my copy, and it turned out to be the 26th printing, but it still said "1st edition".
Here is how to find out what printing of a book you have. First go to the "copyright page". This page will be found behind the "title page", found in the first few pages of any book. This page will have all of the publishing information, ie copyright date, publishing date, name of the author, name of the publisher, and so on. There will also appear there a funny line of numbers, usually at or near the bottom of the page. This line of numbers is the printing sequence, commonly refered to as the "number line". It will look like this;
12345678910 or 10987654321 or 123456789 or 987654321
If you see any one of these number lines, just as it appears above, then your book is in it's first printing. The numbers must be sequential, one, through either nine or ten, or nine or ten through one. If the book were in its second printing it would look like this (I will only use the 9 number line)
234567891 or 198765432---third printing--345678921 or 219876543--and so on (with variations)
NOTE: NOT ALL PUBLISHERS USE THIS METHOD. IF YOUR BOOK DOES NOT HAVE A NUMBER LINE, CONTACT THE PUBLISHER TO FIND OUT THE PRINTING OF THE BOOK.
Okay, so you have now identified your book, through the number line, as a first printing. Before you pop open the champagne bottle, you need to check for one more thing. Look again at the copyright page. Make sure that all the dates on that page correspond. *Make sure that copyright date and the publishing date are the same. **Make sure that there are no previous editions, or publishers. If your book meets all of these tests, then you can be reasonably sure that you have a first printing/first edition, which is the appropriate term for the "1st edition" term now being bantered about on Ebay. Be carefull, ask questions, have fun!!!
*This date may be different in cases where the author is published after their death.
**If an authors makes any changes to a book, after being published, such as adding a chapter, or an adendum, title change, etc, it becomes a new edition. A book can be published by more than one publisher, and the new publisher can state, for example, "first Random house edition" this would not be a true first edition.