For the longest time, blockchains have been only monolithic. We've tried to break this up with things like plasma and sharding but only recently has it become incredibly clear that this is the future or at least the present with rollups and data availability chains like the upcoming Polygon avail.

But, first, what exactly is a monolithic blockchain? To oversimplify, a blockchain performs three basic functions: execution, security, and data availability. For the longest time, a blockchain had to do everything itself, which resulted in crippling inefficiencies, as reflected in the blockchain trilemma. Bitcoin and Ethereum chose to be highly secure and decentralized while sacrificing scalability, whereas other chains made different choices.

Modular chains no longer have to carry the weight of doing everything by itself thus eliminating inefficiencies. So instead of having one monolithic chain, we have three different types or layers.

Execution, which is what users interact with and where all the transactions happen. You won't be able to tell the difference between this and a monolithic blockchain. Rollups are the most important execution layers, but there are also validiums and volitions. Arbitrum One currently has a significant time-to-market advantage, with Polygon looking to drop 4 ZK rollups this year. Both A1 and Polygon's ZK chains, however, are in their early stages. There are more of course and I think the execution layers are going to be the more highly competitive.

Security is by far the most difficult layer of the three. At the moment, there are only two solutions that are sufficiently secure and decentralized, or are attempting to be so: Bitcoin and Ethereum. Most other chains failed to anticipate the blockchain legos tsunami and made crippling sacrifices to security and/or decentralization in order to achieve greater scalability.

Data availability Ethereum also has the best long-term roadmap for data availability, both in terms of technology with KZG commitments and data availability sampling, but also in terms of sheer brute force, leveraging its industry-leading security chain to deploy a large number of data shard chains.

However, Ethereum's data availability layer is likely to be 18 months away. Validiums and volitions can benefit from Ethereum's security in the short term while committing transaction data (in compressed form) to separate data availability layers. We have data availability chains such as Polygon Avail, Celestia, and zkPorter, as well as committees such as StarkEx's DAC that will pick up the slack and have every chance of building network effects. Some of these chains are also security chains, which should be noted.

At the end of the day I believe we are entering a new era of how or blockchain is built and I feel like it is an incredible step forward into the right direction, curious to hear your thoughts.