Many of these international libraries will even loan you material. All that and more is right here. Auction firms have always been a mainstay of buying and selling within the stamp industry. By telephone, mail, e-mail, the internet, or even in person, you can also participate. Here's a sample of current postings.
Stamp collections can consist of dozens or sometimes thousands of the small bits of paper.
How you store them will help track what you have and what you still need. Protecting them is also important.