# From NFT 1.0 to NFT 2.0: A Review of the Evolution of Non-Fungible Tokens
## 1 Introduction
So, by adding more programmability and functionality, NFTs will go beyond artwork and collectibles and change the way we use metadata. The metadata of a dynamic NFT can change due to user interaction. For instance, some game model monsters can be bred as NFTs, and the number of breeds can be stored in the NFT. Some NFTs are also often referred to as \"Living NFTs\", and can have their characteristics change because of a special event or a real-world occurrence, as well as seeing their value and demand shift. One such example is NFTs that evolve based on real-world data changes delivered to the blockchain via oracles [10] or via user interaction as the NFT changes its state [11]. For instance, an NFT card representing a basketball player can show additional data and even unlock traits according to the player's performance [10] ([[https://blog.chain.link/how-lamelo-ball-dynamic-nfts-redefine-player-fan-experience/](https://blog.chain.link/how-lamelo-ball-dynamic-nfts-redefine-player-fan-experience/)]([https://blog.chain.link/how-lamelo-ball-dynamic-nfts-redefine-player-fan-experience/](https://blog.chain.link/how-lamelo-ball-dynamic-nfts-redefine-player-fan-experience/)), accessed on 23 May 2023). Authenticity in dynamic NFTs makes them applicable in various areas. For instance, NFTs could replace passports to travel across the globe without paperwork or stamps [12]. All changes are reflected in the NFT's code, with no chance of fraud or scamming. The same can be carried out for banking accounts, educational certificates, insurance, and any other documentation that gets instantly updated once you input new data. Another crucial aspect related to dynamism is the possibility of introducing randomness fairly and in a provable way through verifiable random functions (VRF). In particular, randomness greatly enhances user experience in play-to-ear games, where players enjoy the fair and random distribution of rare assets and power rankings during in-game campaigns and engagement activities [13]. Considering the societal impact of NFTs on society, it has become of paramount importance to review the evolution of the technology from its 1.0 version to 2.0. This evolution is critical because it completely changes several key properties of NFTs, in particular the possibility to have dynamic metadata, thus opening the opportunity to apply the technology in innovative ways. NFT 2.0 is a complex system that involves the solution of many technical challenges, and it is important to describe its evolution. Therefore, the purpose of this paper is to deliver a complete evolution of NFTs, mentioning what was there before the concept of NFT became a standard, what is the current state of the technology (NFT 1.0), and where NFT 2.0 is leaning. Additionally, we include a discussion concerning the technical challenges related to their on- and off-chain implementation. Shortly, our contribution can be summarised as follows:  
* A review of the technological support offered by the blockchain to NFTs, focusing on the various blockchain network types, their consensus protocols, and their impacts on NFT projects;
* An analysis of NFT 1.0, including a discussion of their properties and standards proposed;
* A comparison between NFT-supporting blockchains in terms of six key properties that define the blockchains' support for NFTs;
* Highlighting innovations of NFT 2.0 with respect to NFT 1.0;
* Pointing out the sources of dynamism for NFT 2.0 metadata, and how metadata can be stored;
* Showcasing the most promising NFT 2.0 applications. The concept of NFT with dynamic metadata is not new to the scientific literature [14]; however, it has not been tackled with the due amount of detail. Indeed, some documents present the topic at a very high level and focus only on arts [15], while others discuss the topic without delving deeper into the technical details, challenges, and opportunities around NFT 2.0 [10].