The 'crossing' or exchanging of books may take any of a number of forms, including wild releasing books in public, direct swaps with other members of the websites, or "book rings" in which books travel in a set order to participants who want to read a certain book. The community aspect of BookCrossing.com has grown and expanded in ways that were not expected at the outset. In addition to forum discussions, mailing lists and annual conventions throughout the world.
In July 2007 Singapore became the first official BookCrossing country in the world. In an initiative was launched together with the National Library of Singapore, 2,000 locations within the country were designated as 'hotspots', similar to Official BookCrossing Zones. In 2008, BookCrossing was introduced to Abu Dhabi as part of a joint venture with the Abu Dhabi Authority for Culture and Heritage.
Anyone who wishes to participate in "releasing" books, whether leaving it in a public place or passing it on to a friend, must register on the BookCrossing.com website, although there is the option to remain anonymous when "catching" or recording the find of a book. BookCrossing.com users can 'go hunting', where a member will go to the website to view a list of books that have recently been "released", then go to the location it was left to "catch" it. Books may also be left at Official BookCrossing Zones" (OBCZs), which are located in certain coffee shops, cafes, restaurants and other public places. The purpose of these locations is to get current members in the area to leave books to share with the public. This also advertises BookCrossing and creates more members.
In March 2005, Caroline Martin, managing director of the publisher Harper Press, said in a speech that "book publishing as a whole has its very own potential Napster crisis in the growing practice of bookcrossing". BookCrossers rebut the link to Napster, saying that whilst music filesharing involves duplicating audio files countless times, BookCrossing doesn't involve duplicating books. Founder, Ron Hornbaker, originally wondered if people would make this comparison when BookCrossing was first launched.