and have been distributed through initial coin offerings. Fees to send ERC-20 tokens must be paid with ether. Non-fungible tokens (NFTs) Ethereum also allows for the creation of unique and indivisible tokens, called non-fungible tokens (NFTs). Since tokens of this type are unique, they have been used to represent such things as collectibles, digital art, sports memorabilia, virtual real estate, and items within games. The first NFT project, Etheria, a 3D map of tradable and customizable hexagonal tiles, was deployed to the network in October 2015 and demonstrated live at DEVCON1 in November of that year. In 2021, Christie's sold a digital image with an NFT by Beeple for , making him the third-most-valuable living artist in terms of auction prices at the time, although observers have noted that both the buyer and seller had a vested interest in driving demand for the artist's work. Land, buildings, and avatars in blockchain-based virtual worlds can also be bought and sold as NFTs, sometimes for hundreds of thousands of dollars. Decentralized finance Decentralized finance (DeFi) offers traditional financial instruments in a decentralized architecture, outside of companies' and governments' control, such as money market funds which let users earn interest. DeFi applications are typically accessed through a Web3-enabled browser extension or application, such as MetaMask, which allows users to directly interact with the Ethereum blockchain through a website. Many of these DApps can connect and work together to create complex financial services. Examples of DeFi platforms include MakerDAO and Compound. Uniswap, a decentralized exchange for tokens on Ethereum grew from in liquidity to in 2020. As of October 2020, over was invested in various DeFi protocols. Additionally, through a process called "wrapping", certain DeFi protocols allow synthetic versions of various assets (such as bitcoin, gold, and oil) to be tradeable on Ethereum and also compatible with all of Ethereum's major wallets and applications. Enterprise software Ethereum-based software and networks, independent from the public Ethereum chain, are being tested by enterprise software companies. Interested parties include Microsoft, IBM, JPMorgan Chase, Deloitte, R3, and Innovate UK (cross-border payments prototype). Barclays, UBS, Credit Suisse, Amazon, Visa, and other companies are also experimenting with Ethereum. Permissioned ledgers Ethereum-based permissioned blockchain variants are used and being investigated for various projects: In 2017, JPMorgan Chase proposed developing JPM Coin on a permissioned-variant of Ethereum blockchain dubbed "Quorum". It is "designed to toe the line between private and public in