Operation and supervision of business facilities for secure, in-person business transactions between buyers and sellers of goods and/or services; Providing a web site whereby buyers of goods or services locate and receive quotations from multiple competitive sources and sellers of goods or services identify and bid on multiple new sales opportunities; Providing an on-line searchable database featuring used books being offered for sale and buyer/seller contact information; Providing an online marketplace for buyers and sellers of goods authenticated by non-fungible tokens (NFTs); Provision of an on-line marketplace for buyers and sellers of goods and services; Provision of an on-line marketplace for buyers and sellers of goods and services; Provision of an online marketplace for buyers and sellers of goods and services; Operating on-line marketplaces for sellers and buyers of goods and/or services