Cosmos SDK is an open source modular development tool framework used to build customized PoS blockchain or PoA blockchain.
The Cosmos SDK allows developers to create blockchains that fit their unique needs, i.e. custom blockchain creation. The Cosmos SDK consists of many modules that can be combined freely. Most of them are open source and readily available to all developers. Developers can choose to use only some of the products provided by the Cosmos SDK. Since it is modular, developers can create different combinations to suit various needs. Just like Lego bricks, developers can choose any module to build their own proprietary blockchain.
In the tool framework of the Cosmos SDK, developers can find the Tendermint consensus mechanism, natively integrated Cosmos ecosystem, IBC protocol, and more. Developers only need to integrate ready-made modules into customized blockchains and modify them according to their respective needs. This makes it easier for developers to create new blockchains without having to write every feature from scratch.
At the same time, the Cosmos SDK is also a powerful framework built by the joint efforts of many developers. Anyone can create new modules for the Cosmos SDK, so they are both a participant and contributor to the Cosmos ecosystem. As the Cosmos network develops, the ecosystem of SDK modules will gradually expand, making the development of complex blockchain applications increasingly easier.
Since Cosmos has been running, many well-known projects have created their own blockchains through the Cosmos SDK, including BNB Chain, Terra before the collapse, Cronos Chain, etc.
Initially, the Cosmos SDK only allowed developers to build applications on top of the Tendermint BFT consensus engine. Over time, the SDK can also be used for other consensus engines that implement the ABCI protocol. Paradigm, for example, has proven that it is possible to create a blockchain by combining the Cosmos SDK with other consensus mechanisms besides Tendermint. Paradigm made a Cosmos/ABCI pilot application using Narwhal/Bullshark adopted by Sui as the consensus algorithm instead of Tendermint. Therefore, more Cosmos SDK architectures compatible with different consensus engines may emerge in the future. We may see more blockchains built on top of the Cosmos SDK using newer, more advanced consensus mechanisms than Tendermint.