A Hitch Hiker is just like the term implies. It's a traveller who relies on the courtesy of others to make his way.
In the Letterboxing world, a Hitch Hiker is a small notebook (usually handmade) and a stamp (usually handmade). The HH is placed in a Letterbox. The next finder stamps their log book with the HH stamp, and then takes it with them and leaves it at their next Letterbox.
It's fun to see where these parcels have originated, where they have been on their journey, and how far they have come!
To make one, You'll need: Some Cardstock, a Printer, a Hole Punch, a Paper Cutter, Some Clear Packing Tape and Some String. Plus, a handmade (or store bought) stamp that you don't care if you never see again. (I explained how to carve your own stamp yesterday).
First print a front and back cover for your book. The whole book should be small (about the size of a credit card) so that it can fit into most letterboxes. Print the name of your book on the cover, who planted it, (your trail name) and the date, plus any other instructions that you may want to give the finders. Be sure to tell the finders to log their finds so that you can track the travels of your book from your computer. Maybe your stamp will determine what the name of the HH will be, for example: if you've carved an eagle, the book could be called "The Soaring Eagle".
Use a paper cutter to cut pages to your book, make them about the same size as the covers to the book. Use clear tape to protect both the front and back covers, to make it somewhat water resistant, and to give the covers some stiffness. Then, punch two holes on the binding side of the book. Take your string, or leather cord, or yarn or whatever, to tie the whole book together.
Put the book and the stamp into a zip-lock bag. Your Hitch Hiker is now ready to begin it's journey! Leave your HH in a Letterbox, Log it's existence, and follow it online.