As Ethereum continues to dominate as a leading platform for decentralized applications, Layer 2 (L2) solutions are pivotal in addressing its scalability and cost issues. In 2024, several L2 projects are leading the way, enhancing Ethereum's capabilities by providing faster transactions and lower fees while maintaining the security and decentralization that the main network offers.

1. Optimism Optimism utilizes Optimistic Rollups to scale the Ethereum network effectively. It allows for a significant reduction in gas fees and improves transaction throughput. The platform supports a vast range of applications and is tightly integrated with Ethereum, meaning anything that operates on Ethereum will seamlessly work on Optimism. It also promises a more communal approach with features like community airdrops.

2. Arbitrum Arbitrum also uses Optimistic Rollups and boasts impressive scalability improvements with transaction speeds and cost reductions. It's particularly appealing to developers looking for Ethereum-compatible environments that do not compromise on security or decentralization.

3. zkSync Employing zero-knowledge rollups, zkSync focuses on maintaining the core principles of Ethereum while significantly boosting its transaction capacity. It is designed for security without compromising the decentralized features of Ethereum, making it a robust choice for projects that prioritize transparency and user sovereignty.

4. Polygon Polygon provides a multi-chain system using zkRollups and Proof-of-Stake mechanisms to enhance scalability. It supports a rich ecosystem including DeFi apps and NFT marketplaces, and is known for its high transaction throughput and low fees, which have made it a popular choice among developers and users alike.

5. StarkNet Using a unique approach with STARK proofs, StarkNet offers scalability and privacy. It processes transactions off-chain and achieves high throughput and low transaction costs. StarkNet supports a variety of applications, particularly those requiring high computational efficiency.

6. Immutable X Focused on the gaming and NFT sectors, Immutable X uses zk-rollup technology to provide rapid transactions and high scalability, supporting a vibrant ecosystem of web3 gaming applications without gas fees.

7. Base Developed by Coinbase, Base aims to simplify access to blockchain technology with lower costs and faster transaction speeds using Optimistic Rollups. It's designed to be a developer-friendly layer that inherits the security of Ethereum while enhancing its scalability.

Each of these projects contributes uniquely to solving Ethereum’s scalability challenge. By leveraging technologies like rollups and modular blockchains, they provide viable solutions that uphold Ethereum's decentralized ethos while increasing its capacity for broader adoption and more complex applications. These advancements represent critical steps toward a more efficient and user-friendly blockchain ecosystem in 2024.