"Layer 3" is not a widely recognized or standardized concept in the context of blockchain or networking technology. In traditional networking, the OSI (Open Systems Interconnection) model defines seven layers, with Layer 3 being the Network Layer responsible for routing and forwarding data packets between different networks. However, this model is not directly applicable to blockchain technology.

In some discussions, particularly related to blockchain and Layer 2 scaling solutions, you may encounter references to "Layer 3" as the "Application Layer." In this context, it is a more informal way of categorizing the different layers or components within a blockchain ecosystem:

1. Layer 1 (L1): The Base Layer, which includes the core blockchain infrastructure, consensus mechanism, and data storage.
2. Layer 2 (L2): Scaling Solutions, which address scalability and performance issues by processing transactions off-chain or through sidechains.
3. Layer 3 (L3): The Application Layer, where decentralized applications (DApps), smart contracts, and various blockchain-based services are built and deployed for end-users.

Layer 3, or the Application Layer, is where developers create and deploy applications that interact with the underlying blockchain infrastructure. These applications leverage the security and trustlessness of the blockchain to offer various services, such as decentralized finance (DeFi), non-fungible tokens (NFTs), supply chain tracking, and more.

It's important to note that the use of "Layer 3" in this context is not a standardized terminology, and it's more of a conceptual framework to categorize the different components of a blockchain ecosystem. The primary layers that are consistently recognized in the blockchain industry are Layer 1 and Layer 2, as described in previous responses.