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A large number of pen-pals today like to swap. Stationary, FBs, postcards ... you name it. Chances are someone somewhere collects it and someone else is willing to trade for it. Swapping is a great way to build personal collections as well as give and receive gifts through the mail. Some of the items people list as swaps are self-explanatory, but unless you've been pen-palling for a while, you may not know the lingo. FBs? Decos? What the ...?
FRIENDSHIP BOOKS (FBS)
Friendship books, or FB's for short, are very common among swappers. These are handmade booklets small enough to fit into an envelope, usually no more than five or six pieces of paper stapled together. On the front of the FB will be a FOR address and a BY address. Sometimes these are the same, if the person made the FB for themselves. On the last page is something along the lines of "When full, send home." The FB can be decorated with pictures, stickers, labels, drawings, glitter ... the possibilities are endless.

The person who creates the FB mails it to a pen-pal or swapper who trades them. This person adds his or her name and address, as well as any personal information they want other potential pen-pals to know. Since there isn't much room on an FB, this information is usually abbreviated to almost code-like phrases. Some common FB abbreviations include:

A/A — Answers All pen-pals who write
A/M — Answers Most people
A/O — Answers Only (usually lists what type of pals they're looking for)
A/S — Answers Some (so many your letter stand out!)
SNNP — Sorry, No New Pals
DOB — Date of Birth (also BD, for birthday)
GLBT — Gay, Lesbian, Bisexual, Transgender
ICR — I Can Return (the person is willing to mail the full FB to its owner)
LLPs — Long Letter Pals
N/M — No Men
N/P — No Prisoners
NPW — New Pals Wanted (also NSW, for New Swappers)
SAHM — Stay At Home Mom
US Only — Only wants pen-pals/swappers in the US
WA — Wedding Anniversary (also WD, for Wedding Date)
WW — World Wide
WS — Write Soon
Once one person has signed the FB, either with their address or the words "passing through" (meaning they don't want to put their address in there), then they mail it onto someone else. It passes through the mail like this, from person to person, sometimes going all over the world before it's completely filled. The last person to sign it sends the full FB to the name and address that it is intended for.
The main thing with FBs is to pass them on. Sign them or not, but don't just throw them out or let them sit in your room forever. Mail them to someone else and keep them moving until they're sent home. If you get an FB and don't have anyone to send it to, pick someone's name out of the FB and write to them. Or you can mail it to the owner, even though it isn't full. People would rather get them back than never see them at all.

Friendship Sheets (FS) are like FBs but are only one page of paper. Once both sides are filled, it is sent home.

DECOS
Decos are FBs that are more artistic. They usually have themes, like "Black and White Deco" or "Vacation Deco." Each person who signs the deco (which stands for "decorative") book gets a page to fill. On that page, they tape or glue pictures — from magazines, postcards, greeting cards — or decorate it with colored paper, glitter, stickers, images, etc. If it's a themed deco, then you should try to keep your decorated page in the same theme. For instance, a "Black and White Deco" theme could include B&W photos you cut from a magazine. A "Sea Theme" deco could have pictures of surfers, the beach, fish, or the ocean. When full, return the deco to its owner. If you are uncomfortable with decorating a page or don't wish to contribute, simply pass it on. DO NOT just stick a label in the deco and send it to someone else. That is considered rude, since you just "wasted" a full page and didn't participate.

SLAMS
Slams are similar to the slam books you might have passed along to your friends in high school. They are FBs with several pages. The first is the sign in page, where you put your name and address. Some slams have numbers to keep track of the people who sign in; some simply ask that you chose a symbol and place it next to your answer on each consecutive page. Every other page in the slam will have a question — "How old are you?" or "What is your favorite TV show?" Some are theme slams — for instance, a "Music Slam" would only have questions pertaining to the type of music you like. When you have answered all of the questions, you mail it to someone else.

CRAMS
Crams are very small FBs. The point is to cram as many addresses onto it as possible. Usually you don't write much personal information, just your name and address. Some crams are called LABELS, and are for address labels only.

LABEL/STICKER BAGS
These can be fun — basically, it is a small coin or handmade envelope with an address on the outside. This is who the bag should be mailed to when full. For a label bag, you usually stick in 1-5 of your own address labels. The purpose is that when the owner gets the bag back, he or she will use your labels to make FBs for you. A sticker bag usually asks that you place a few unused stickers inside and send onto someone else. You should follow any directions on the bag — for example, some ask that you take as many stickers/labels out that you put in, some ask that you don't remove anything from inside. When full, send home to the owner.

LYRIX, QUOTEZ, ETC.
There are many different types of FBs. Lyrix are like deco books, only you decorate a page with lyrics from your favorite song. Quotez, same thing, only with quotations.

FINALLY ...
There are no limits to what you can swap. Some FBs are for "mommies" only (women with children), some specifically ask that you don't mail them overseas, some request that you don't mail them to prisons or particularly countries. Whatever the case, make sure you follow any directions that are written on the FB and that you mail it out in a timely manner. Remember that what you write will be seen by everyone who receives the FB, so keep it respectful. Use labels or print CLEARLY so that others who want to write to you can read your address. It's usually a good idea to date it, as well, so the owner will know how long it took to circulate.

FBs are excellent ways to meet new pen-pals from all over the world. Don't hesitate to write to anyone listed in an FB (unless they specifically state that they do not want any new pen-pals at this time). They are an excellent way to get your name out there and meet new people, as well as a good outlet for creativity.

SOURCE: http://pals.jherusalem.com/fbs.html