Dencum is a significant update that recently launched on March 13, 2024. Here's a quick rundown:

Focuses on Scalability: Dencun is one of the most anticipated upgrades since the Merge, aiming to improve Ethereum's scalability.

Proto-Danksharding (EIP-4844): The core feature of Dencun is the introduction of proto-danksharding, also known as EIP-4844. This paves the way for a future sharding implementation, which will significantly increase transaction throughput on the network.

Impact on Layer 2 Fees: Dencun is expected to reduce transaction fees for Layer 2 scaling solutions by introducing a new type of transaction called "blobs." This could make Ethereum more accessible and attractive for users.

Milestone for Ethereum: The successful launch of Dencun is a major milestone for Ethereum's roadmap, bringing it closer to becoming a more scalable and efficient platform.

• Focus on Scalability: Ethereum has faced criticism for its slow transaction speeds and high fees. Dencun is a significant step towards addressing these issues.
• Proto-Danksharding (EIP-4844): This is the core feature of Dencun. It introduces "blobs," a new type of data storage on the Ethereum mainnet. These blobs offer a cheaper way to store transaction data compared to the traditional "calldata" method used by Layer 2 rollups.
• Reduced Fees for Layer 2 Networks: By making data storage cheaper, Dencun paves the way for significantly lower transaction fees on Layer 2 scaling solutions like Arbitrum and Polygon. This can make Ethereum more accessible and attractive for a wider range of users.
• Milestone for Ethereum: The successful launch of Dencun is a major accomplishment for Ethereum. It demonstrates progress towards its goal of becoming a more scalable and efficient platform for decentralized applications (dApps).

• Dencun doesn't directly reduce fees on the main Ethereum blockchain (Layer 1). However, by making Layer 2 rollups more efficient, it indirectly benefits a large portion of Ethereum users who rely on these solutions.
• The upgrade doesn't lead to a direct increase in the number of transactions per block on either Layer 1 or Layer 2. However, it creates conditions for faster transaction processing on Layer 2, which could indirectly allow these networks to handle more transactions over time.

Overall, the Dencun upgrade is a significant step forward for Ethereum's scalability. It paves the way for lower fees and faster transaction processing, making the platform more usable and attractive for developers and users.

Upgrade Specification The Dencun upgrade combines changes to both Ethereum's consensus and execution layers. The full list of protocol changes can be found in EIP-7569. For reference, they are:

• EIP-1153: Transient storage opcodes
• EIP-4788: Beacon block root in the EVM-
• EIP-4844: Shard Blob Transactions
• EIP-5656: MCOPY - Memory copying instruction
• EIP-6780: SELFDESTRUCT only in same transaction
• EIP-7044: Perpetually Valid Signed Voluntary Exits
• EIP-7045: Increase Max Attestation Inclusion Slot
• EIP-7514: Add Max Epoch Churn Limit
• EIP-7516: BLOBBASEFEE opcode

Deneb

Complete python specifications for changes affecting Ethereum's consensus layer can be found in the deneb folder of the ethereum/consensus-specs repository.

Cancun

The EIPs linked above contain the full specifications for changes affecting Ethereum's execution layer. Additionally, a python specification for these is being implemented in the ethereum/execution-specs repository. Lastly, Deneb requires changes to the Engine API, used for communication between the consensus and execution layer nodes. These are specified in the cancun.md file of the ethereum/execution-apis repository.