Operating on-line marketplaces for sellers and buyers of goods and/or services; Providing a website featuring an online marketplace for exchanging goods and services with other users; Providing an online marketplace featuring downloadable images files of apartments for use in virtual worlds; Providing an online marketplace for buyers and sellers of goods authenticated by non-fungible tokens (NFTs); Providing health insurance exchanges in the nature of a marketplace that offers purchasers of health insurance a variety of plans from different insurance providers; Provision of an on-line marketplace for buyers and sellers of goods and services; Provision of an online marketplace for buyers and sellers of downloadable digital art images authenticated by non-fungible tokens (NFTs); Provision of an online marketplace for buyers and sellers of downloadable digital image files authenticated by non-fungible tokens (NFTs); Provision of an online marketplace for buyers and sellers of downloadable image files authenticated by non-fungible tokens (NFTs); Provision of an online marketplace for buyers and sellers of downloadable music files authenticated by non-fungible tokens (NFTs); Provision of an online marketplace for buyers and sellers of downloadable video files authenticated by non-fungible tokens (NFTs); Provision of an online marketplace for buyers and sellers of goods and services; Provision of an online marketplace for buyers and sellers of image files of virtual real estate authenticated by non-fungible tokens (NFTs); Provision of an online marketplace, using blockchain technology, for buyers and sellers of downloadable digital art images authenticated by non-fungible tokens (NFTs)