>90% of L2 transaction costs are due to L1 call-data storage. With EIP-4844, Ethereum can store temporary blobs of data for 1 year so L2s can pay significantly less in fees.
As an example, the cost for a single Uniswap transaction could go from ~$1 down to ~$0.1 or less!
To prevent blobs being filled with spam, a separate blob data fee market will be used to determine the cost of blob storage. Stay tuned for more dashboards and tools.For more on 4844
What is Dencun?
Since Proof-of-Stake, ETH is broken into the execution and consensus layers. Dencun requires both layers to be upgraded: Dencun (consensus) & Cancun (executio). EIP-4844 is part of the execution upgrade.