Bitcoin 3.0 is an informal label used by some projects, writers and marketers for a supposed next stage in Bitcoin's development. There is no official Bitcoin 3.0 and no upgrade by that name; Bitcoin changes only through formal improvement proposals adopted by node operators. The phrase usually refers to building smart contracts, layer 2 networks, tokens and decentralized applications on or around Bitcoin, often through projects such as Stacks, Rootstock or BitVM. It echoes the generational language of Blockchain 3.0. Some token projects have also used names like "Bitcoin 3.0" for unrelated coins, so buyers should treat the term with caution and check what is actually being offered. Also see Bitcoin Blockchain.