Since the 1990s, the large postal operators of the world have sought for
more economic and more secure forms of postage than traditional stamps and
postage meters. Since the early 2000s postal liberalization gains more
momentum in some markets and has created a number of private postal operators
that compete with the universal postal operators. As the private postal
operators grow bigger, they develop similar demands for economic and secure
evidence of prepaid postage on the mail they process.