Non-fungible tokens (NFTs) are unique digital assets that represent verifiable ownership of items such as art, collectibles and virtual property. Enabled by blockchain technology and smart contracts, NFTs differ from fungible assets like Bitcoin in that each token is indivisible and distinct. Early experiments with NFTs began on platforms like Namecoin and Bitcoin, but widespread adoption was driven by Ethereum due to its programmable infrastructure and the introduction of NFT standards like ERC721 and ERC1155. These standards formalized NFT creation, ownership and transfer, fostering interoperability across decentralized applications. Smart contracts, primarily written in Solidity, provide the automation and logic behind NFT functionality, ensuring secure and immutable transactions. ERC721 defines a framework for unique, single-token ownership, while ERC1155 introduces a multi-token model supporting both fungible and non-fungible assets with greater efficiency. Recent innovations such as inscriptions store metadata directly in blockchain transaction calldata, as seen with Bitcoin Ordinals. This demonstrates new approaches to digital asset representation beyond traditional token standards. NFTs continue to evolve as a foundational technology for digital ownership and decentralized economies.