Assignment - When a photobuyer contracts with you to make a specific image(s). All terms are generally agreed upon in advance. The resulting photo copyright(s) belong to you unless otherwise stated in writing.
Commercial - Basically the difference between commercial and editorial is that the commercial photographer makes images primarily for advertising, endorsement, or promotion, while the editorial photographer sticks to the editorial side of things. A model release and/or property release is required for commercial work, whereas editorial work generally does not require such releases. There are exceptions to every rule, and this is no exception.
Duplicates - Also referred to as dupes. Some photobuyers prefer to see dupes instead of originals. Best to check first. However, a dupe is a second generation of the original and often unusable for any size larger than ¼ page.
Editorial - Editorial photographs usually illustrate a concept in an article or story, in a book, magazine or newspaper. They are sometimes documentation of a subject. Generally speaking, creative editorial stock photographers "make" a photo, rather than "take" a photo.
Holding fee - A fee you will be able to charge photobuyers when your name has been out there for a while and they know who you are. Most beginners should not charge a holding fee, simply because not very many photobuyers look favorably on a newcomer to the trade who assumes to charge the fee. Instead, mention in your cover letter with your submission, that the photobuyer is welcome to hang on to your images for a specific length of time without a holding fee, usually two weeks. When you are established, a standard fee to charge is 1 cent per transparency; less for a B&W. With the advent of digital submissions, holding fees are fading from use.
Image Submission Sheet - A simple sheet that you send along with your image submission of photos, that allows the photobuyer to quickly and easily let you know if and why he or she needs to hang on to your images for a while. Also see "Stock Photographer Starter Kit".
In-camera Duplicates - Basically means to snap more than one frame of the same thing. The cheapest way to assure you that you have plenty of slides of a particular subject.
Slide Labels - Crucial to making a good first impression when submitting images. Also a good way of getting captions on your images. Also see "Stock Photographer Starter Kit".
Manila Envelopes - Avoid them. See Packaging, below.
Model Release - Rarely needed for editorial stock. Almost always required for commercial work. See the "Kracker Barrel" archives for more information on this, at http://www.photosource.com/board/wwwboard/wwwboard.html
Packaging - Perhaps the single most important part of your submission, aside from your images. Spend some extra money on getting deluxe packaging material: mailing cartons, envelopes, mailing labels, etc. Every dollar spent on these items will be a dollar wisely spent. Use white packaging envelopes rather than the common manila envelopes. Photobuyers are extremely busy people and a package that doesn't look professional often gets put aside and perhaps not even looked at. Professional packaging gets your submission over the initial threshold, makes it more likely that the photobuyer will actually look at your images. ("You never get a second chance to make a first impression.")
Payment on Acceptance - Means that a photobuyer will pay you when your image is accepted for publication, not waiting for when it's actually published. The number of days before the payment is issued varies, though. Always insist on "Payment on Acceptance."
Payment on Publication - Means that a photobuyer will pay you after your image is published (normally within 60 days after publication). Avoid photobuyers who "Pay on Publication."
Photobuyer - The people that buy images. Photo Editors, Art Directors, Designers, Book Publishers, and so on.
Photo Guidelines - Informative sheet(s) you should request from all photobuyers you want to submit images to. Photo guidelines inform you of specific details about that market's standard operating procedures, such as payment ranges, film size and preference, as well as their editorial lineup for future subjects. Send them a request for photo guidelines on good quality stationery, with your letterhead, and include a SASE.