docs: update learn/intro (backport #22046) (#22079)

Co-authored-by: Julián Toledano <[email protected]>

docs/learn/intro/00-overview.md

@@ -9,13 +9,13 @@ sidebar_position: 1
 The [Cosmos SDK](https://github.com/cosmos/cosmos-sdk) is an open-source toolkit for building multi-asset public Proof-of-Stake (PoS) <df value="blockchain">blockchains</df>, like the Cosmos Hub, as well as permissioned Proof-of-Authority (PoA) blockchains. Blockchains built with the Cosmos SDK are generally referred to as **application-specific blockchains**.
 
 The goal of the Cosmos SDK is to allow developers to easily create custom blockchains from scratch that can natively interoperate with other blockchains. 
-We further this modular approach by allowing developers to plug and play with different consensus engines this can range from the [CometBFT](https://github.com/cometbft/cometbft) or [Rollkit](https://rollkit.dev/). 
+We further this modular approach by allowing developers to plug and play with different consensus engines this can range from [CometBFT](https://cometbft.com/) or [Rollkit](https://rollkit.dev/). 
 
 SDK-based blockchains have the choice to use the predefined modules or to build their own modules. What this means is that developers can build a blockchain that is tailored to their specific use case, without having to worry about the low-level details of building a blockchain from scratch. Predefined modules include staking, governance, and token issuance, among others.
 
 What's more, the Cosmos SDK is a capabilities-based system that allows developers to better reason about the security of interactions between modules. For a deeper look at capabilities, jump to [Object-Capability Model](../advanced/10-ocap.md).
 
-How you can look at this is if we imagine that the SDK is like a lego kit. You can choose to build the basic house from the instructions or you can choose to modify your house and add more floors, more doors, more windows. The choice is yours.
+You can think of the SDK as a lego kit. You can choose to build the basic house from the instructions, or you can choose to modify your house and add more floors, more doors, more windows. The choice is yours.
 
 ## What are Application-Specific Blockchains
 
@@ -27,17 +27,17 @@ Learn more about [application-specific blockchains](./01-why-app-specific.md).
 
 ## What is Modularity
 
-Today there is a lot of talk around modularity and discussions between monolithic and modular. Originally the Cosmos SDK was built with a vision of modularity in mind. Modularity is derived from splitting a blockchain into customizable layers of execution, consensus, settlement and data availability, which is what the Cosmos SDK enables. This means that developers can plug and play, making their blockchain customisable by using different software for different layers. For example you can choose to build a vanilla chain and use the Cosmos SDK with CometBFT. CometBFT will be your consensus layer and the chain itself would be the settlement and execution layer. Another route could be to use the SDK with Rollkit and Celestia as your consensus and data availability layer. The benefit of modularity is that you can customize your chain to your specific use case.
+Today, there is a lot of talk around modularity and discussions between monolithic and modular. Originally, the Cosmos SDK was built with a vision of modularity in mind. Modularity is derived from splitting a blockchain into customizable layers of execution, consensus, settlement and data availability, which is what the Cosmos SDK enables. This means that developers can plug and play, making their blockchain customizable by using different software for different layers. For example, you can choose to build a vanilla chain and use the Cosmos SDK with CometBFT. CometBFT will be your consensus layer and the chain itself would be the settlement and execution layer. Another route could be to use the SDK with Rollkit and [Celestia](https://celestia.org/) as your consensus and data availability layer. The benefit of modularity is that you can customize your chain to your specific use case.
 
 ## Why the Cosmos SDK
 
 The Cosmos SDK is the most advanced framework for building custom modular application-specific blockchains today. Here are a few reasons why you might want to consider building your decentralized application with the Cosmos SDK:
 
-* It allows you to plug and play and customize your consensus layer. As above you can use Rollkit and Celestia as your consensus and data availability layer. This offers a lot of flexibility and customisation. 
-* Previously the default consensus engine available within the Cosmos SDK is [CometBFT](https://github.com/cometbft/cometbft). CometBFT is the most (and only) mature BFT consensus engine in existence. It is widely used across the industry and is considered the gold standard consensus engine for building Proof-of-Stake systems.
+* It allows you to plug and play and customize your consensus layer. As mentioned above, you can use Rollkit and Celestia as your consensus and data availability layer. This offers a lot of flexibility and customization. 
+* Previously the default consensus engine available within the Cosmos SDK is [CometBFT](https://cometbft.com/). CometBFT is the most (and only) mature BFT consensus engine in existence. It is widely used across the industry and is considered the gold standard consensus engine for building Proof-of-Stake systems.
 * The Cosmos SDK is open-source and designed to make it easy to build blockchains out of composable [modules](../../build/modules). As the ecosystem of open-source Cosmos SDK modules grows, it will become increasingly easier to build complex decentralized platforms with it.
 * The Cosmos SDK is inspired by capabilities-based security, and informed by years of wrestling with blockchain state-machines. This makes the Cosmos SDK a very secure environment to build blockchains.
-* Most importantly, the Cosmos SDK has already been used to build many application-specific blockchains that are already in production. Among others, we can cite [Cosmos Hub](https://hub.cosmos.network), [IRIS Hub](https://irisnet.org), [Binance Chain](https://docs.binance.org/), [Terra](https://terra.money/) or [Kava](https://www.kava.io/). [Many more](https://cosmos.network/ecosystem) are building on the Cosmos SDK.
+* Most importantly, the Cosmos SDK has already been used to build many application-specific blockchains that are already in production. Among others, we can cite [Cosmos Hub](https://hub.cosmos.network), [Osmosis](https://osmosis.zone/), [Binance Chain](https://docs.binance.org/), [Terra](https://terra.money/) or [Dydx](https://dydx.exchange/). [Many more](https://cosmos.network/ecosystem) are building on the Cosmos SDK.
 
 ## Getting started with the Cosmos SDK
 

docs/learn/intro/02-sdk-app-architecture.md

@@ -54,7 +54,7 @@ flowchart LR
     A -->|"For each T in B: apply(T)"| B
 ```
 
-In a blockchain context, the state machine is deterministic. This means that if a node is started at a given state and replays the same sequence of transactions, it will always end up with the same final state.
+In a blockchain context, the state machine is [deterministic](https://en.wikipedia.org/wiki/Deterministic_system). This means that if a node is started at a given state and replays the same sequence of transactions, it will always end up with the same final state.
 
 The Cosmos SDK gives developers maximum flexibility to define the state of their application, transaction types and state transition functions. The process of building state machines with the Cosmos SDK will be described more in-depth in the following sections. But first, let us see how the state machine is replicated using various consensus engines, such as CometBFT.
 
@@ -117,7 +117,7 @@ Note that **CometBFT only handles transaction bytes**. It has no knowledge of wh
 
 Here are the most important messages of the ABCI:
 
-* `CheckTx`: When a transaction is received by CometBFT, it is passed to the application to check if a few basic requirements are met. `CheckTx` is used to protect the mempool of full-nodes against spam transactions. . A special handler called the [`AnteHandler`](../beginner/04-gas-fees.md#antehandler) is used to execute a series of validation steps such as checking for sufficient fees and validating the signatures. If the checks are valid, the transaction is added to the [mempool](https://docs.cometbft.com/v1.0/explanation/core/mempool) and relayed to peer nodes. Note that transactions are not processed (i.e. no modification of the state occurs) with `CheckTx` since they have not been included in a block yet.
+* `CheckTx`: When a transaction is received by CometBFT, it is passed to the application to check if a few basic requirements are met. `CheckTx` is used to protect the mempool of full-nodes against spam transactions. A special handler called the [`AnteHandler`](../beginner/04-gas-fees.md#antehandler) is used to execute a series of validation steps such as checking for sufficient fees and validating the signatures. If the checks are valid, the transaction is added to the [mempool](https://docs.cometbft.com/v1.0/explanation/core/mempool) and relayed to peer nodes. Note that transactions are not processed (i.e. no modification of the state occurs) with `CheckTx` since they have not been included in a block yet.
 * `DeliverTx`: When a [valid block](https://docs.cometbft.com/v1.0/spec/core/data_structures#block) is received by CometBFT, each transaction in the block is passed to the application via `DeliverTx` in order to be processed. It is during this stage that the state transitions occur. The `AnteHandler` executes again, along with the actual [`Msg` service](../../build/building-modules/03-msg-services.md) RPC for each message in the transaction.
 * `BeginBlock`/`EndBlock`: These messages are executed at the beginning and the end of each block, whether the block contains transactions or not. It is useful to trigger automatic execution of logic. Proceed with caution though, as computationally expensive loops could slow down your blockchain, or even freeze it if the loop is infinite.
 
@@ -136,4 +136,4 @@ If we use the example of Rollkit, a user initiates a transaction, which is then
 
 The Interoperability Layer enables communication and interaction between different blockchains. This layer facilitates cross-chain transactions and data sharing, allowing various blockchain networks to interoperate seamlessly. Interoperability is key for building a connected ecosystem of blockchains, enhancing their functionality and reach.
 
-In this case we have separated the layers even further to really illustrate the components that make-up the blockchain architecture and it is important to note that the Cosmos SDK is designed to be interoperable with other blockchains. This is achieved through the use of the Inter-Blockchain Communication (IBC) protocol, which allows different blockchains to communicate and transfer assets between each other.
+In this case we have separated the layers even further to really illustrate the components that make-up the blockchain architecture and it is important to note that the Cosmos SDK is designed to be interoperable with other blockchains. This is achieved through the use of the [Inter-Blockchain Communication (IBC) protocol](https://www.ibcprotocol.dev/), which allows different blockchains to communicate and transfer assets between each other.

docs/learn/intro/03-sdk-design.md

@@ -22,7 +22,7 @@ Here is a simplified view of how transactions are handled by an application buil
 Here is an example of this from `simapp`, the Cosmos SDK demonstration app:
 
 ```go reference
-https://github.com/cosmos/cosmos-sdk/blob/v0.50.0-alpha.0/simapp/app.go#L170-L212
+https://github.com/cosmos/cosmos-sdk/blob/v0.52.0-beta.1/simapp/app.go#L145-L186
 ```
 
 The goal of `baseapp` is to provide a secure interface between the store and the extensible state machine while defining as little about the state machine as possible (staying true to the ABCI).
@@ -33,7 +33,7 @@ For more on `baseapp`, please click [here](../advanced/00-baseapp.md).
 
 The Cosmos SDK provides a [`multistore`](../advanced/04-store.md#multistore) for persisting state. The multistore allows developers to declare any number of [`KVStores`](../advanced/04-store.md#base-layer-kvstores). These `KVStores` only accept the `[]byte` type as value and therefore any custom structure needs to be marshalled using [a codec](../advanced/05-encoding.md) before being stored.
 
-The multistore abstraction is used to divide the state in distinct compartments, each managed by its own module. For more on the multistore, click [here](../advanced/04-store.md#multistore)
+The multistore abstraction is used to divide the state in distinct compartments, each managed by its own module. For more on the multistore, click [here](../advanced/04-store.md#multistore).
 
 ## Modules
 
@@ -61,6 +61,6 @@ Cosmos SDK modules are defined in the `x/` folder of the Cosmos SDK. Some core m
 
 * `x/auth`: Used to manage accounts and signatures.
 * `x/bank`: Used to enable tokens and token transfers.
-* `x/staking` + `x/slashing`: Used to build Proof-Of-Stake blockchains.
+* `x/staking` + `x/slashing`: Used to build Proof-of-Stake blockchains.
 
-In addition to the already existing modules in `x/`, that anyone can use in their app, the Cosmos SDK lets you build your own custom modules. You can check an [example of that in the tutorial](https://tutorials.cosmos.network/).
+In addition to the already existing modules in `x/`, which anyone can use in their app, the Cosmos SDK lets you build your own custom modules. You can check an [example of that in the tutorial](https://tutorials.cosmos.network/).

docs/learn/learn.md

@@ -3,8 +3,8 @@ sidebar_position: 0
 ---
 # Learn
 
-*   [Introduction](./intro/00-overview.md) -  Dive into the fundamentals of Cosmos SDK with an insightful introduction,
-laying the groundwork for understanding blockchain development. In this section we provide a High-Level Overview of the SDK, then dive deeper into Core concepts such as Application-Specific Blockchains, Blockchain Architecture, and finally we begin to explore what are the main components of the SDK.
+*   [Introduction](./intro/00-overview.md) - Dive into the fundamentals of Cosmos SDK with an insightful introduction,
+laying the groundwork for understanding blockchain development. In this section, we provide a High-Level Overview of the SDK, then dive deeper into Core concepts such as Application-Specific Blockchains, Blockchain Architecture, and finally, we begin to explore the main components of the SDK.
 *   [Beginner](./beginner/00-app-anatomy.md) - Start your journey with beginner-friendly resources in the Cosmos SDK's "Learn"
 section, providing a gentle entry point for newcomers to blockchain development. Here we focus on a little more detail, covering the Anatomy of a Cosmos SDK Application, Transaction Lifecycles, Accounts and lastly, Gas and Fees.
 *   [Advanced](./advanced/00-baseapp.md) - Level up your Cosmos SDK expertise with advanced topics, tailored for experienced