Barb,
a swap is where some picks a theme and is the then the host of this swap.
The host decides how many elements the swap will have, limit the number of swapers if desired.
Then each person signs up for an element such as paper piecing (PP), eyelets, tags etc...
you then make one for each person in the swap including yourself.
You then put them in bags and mail them to the host. Once she has everyones items she send them out to all of the people who participated.
This last swap I made 20 toppers in return I rec'd 20 hand made items.
Does that help?
Swaps are tons of fun! you should give it a try! This board is a wonderful place to begin swaping. Everyone is so encouraging and really puts their best foot forward!