A limited edition book is one where the number of copies in the print run has been strictly defined prior to its issue, and that number is substantially less than a standard print run, and then no further print runs are issued after the first printing has sold out.
Limited editions can also be stand alone releases such as a novella or short story where the limited edition is the only time the author plans to release that work for purchase. Alternately a limited edition may be published in conjunction with a standard print run with the limited edition containing additional features such as better quality paper, extra illustrations, signatures, different cover art, a slip case, or something else not normally included in a book from that author or publisher.
One of the most famous publishers of limited editions is the Limited Editions Club with many famous illustrators have worked for them.
Things to consider with limited editions
Just because a book is a limited edition does not always mean it is rare or collectible or valuable; always pay attention to the number of copies printed as supply can still outstrip demand with limitations.
Limited editions are designed to be collectible. Owners are far less likely to allow damage or thumbing of their limited editions meaning a larger percentage will be in fine condition even after long periods of time.
A numbered edition is a limited edition where the total number of copies in the print run is notated on the book. This is usually written as the current number over the total number in the printing; for example: “This book is copy number 54/200”.
A lettered edition is the same as a numbered edition except with letters. They are nearly always limited to 26 copies and each one is denoted by a different letter of the alphabet. Occasionally lettered editions will be limited to 52 copies (with upper and lower case letters) and sometimes even fewer than 26 copies, although this is rare.
A publisher may release something called a deluxe edition which contains additional features (extra illustrations, extra stories, etc) but this does not necessarily mean it’s limited or collectable. Use due diligence to check if a deluxe edition is not simply a fluffed up hardback with a higher price.