# Blockchain foundations overview (https://docs.ton.org/llms/foundations/overview/content.md)



## Data and serialization [#data-and-serialization]

TON stores data as graphs of cells and serializes those graphs for messages, blocks, account state, proofs, and storage.

* [TL-B](https://docs.ton.org/llms/foundations/tlb/overview/content.md): how TON data structures are defined and serialized.
* [Cells](https://docs.ton.org/llms/foundations/serialization/cells/content.md): basic storage units used by TVM, persistent storage, and smart contract code.
* [Library references](https://docs.ton.org/llms/foundations/serialization/library/content.md): cells that point to published library cells by hash.
* [Merkle proofs](https://docs.ton.org/llms/foundations/serialization/merkle/content.md): exotic cells that prove selected data belongs to a larger cell tree.
* [Merkle updates](https://docs.ton.org/llms/foundations/serialization/merkle-update/content.md): exotic cells that describe a verified transition between two cell trees.
* [Pruned branches](https://docs.ton.org/llms/foundations/serialization/pruned/content.md): compact replacements for deleted subtrees.
* [Bag of Cells](https://docs.ton.org/llms/foundations/serialization/boc/content.md): the standard format for transferring or storing cell graphs.

Read about using Merkle cells for the verification of selected blockchain data in smart contracts and off-chain software: [Proofs overview](https://docs.ton.org/llms/foundations/proofs/overview/content.md).

## Accounts and transactions [#accounts-and-transactions]

What happens to accounts before, during, and after transaction execution.

* [Addresses](https://docs.ton.org/llms/foundations/addresses/overview/content.md): how accounts are identified and how smart contracts exchange messages.
* [Messages and transactions](https://docs.ton.org/llms/foundations/messages/overview/content.md): contract execution triggers and records of the resulting account state changes.
* [Actions](https://docs.ton.org/llms/foundations/actions/overview/content.md): how smart contracts queue operations to be performed during the action phase.
* [Account status](https://docs.ton.org/llms/foundations/status/content.md): whether an account can store balance, hold code, or process transactions.
* [Execution phases](https://docs.ton.org/llms/foundations/phases/content.md): the storage, credit, compute, action, and bounce phases that can make up a transaction.
* [Transaction fees](https://docs.ton.org/llms/foundations/fees/content.md): storage, compute, import, forward, and action costs during transaction processing.
* [Traces](https://docs.ton.org/llms/foundations/traces/content.md): causally related messages and transactions grouped into one operation flow.

## Network and configuration [#network-and-configuration]

How TON scales, enforces limits, and stores network parameters.

* [Blockchain sharding](https://docs.ton.org/llms/foundations/shards/content.md): how workchains split into shardchains that process account activity in parallel.
* [Blockchain limits](https://docs.ton.org/llms/foundations/limits/content.md): maximum sizes, depths, gas values, and other network constraints.
* [Blockchain configuration](https://docs.ton.org/llms/foundations/config/content.md): values that influence validator behavior, fees, capabilities, and system contracts.
* [Web3 services](https://docs.ton.org/llms/foundations/web3/overview/content.md): TON Network, TON Storage, TON Proxy, TON DNS, and TON Sites.
* [System contracts](https://docs.ton.org/llms/foundations/system/content.md): contracts that manage validator elections and blockchain configuration.
* [Precompiled contracts](https://docs.ton.org/llms/foundations/precompiled/content.md): contracts with native implementations in validator nodes.

## Consensus [#consensus]

How validators exchange dependent messages and prepare data for consensus: [Catchain consensus](https://docs.ton.org/llms/foundations/consensus/catchain-overview/content.md).

## Whitepapers [#whitepapers]

Original and new TON whitepapers:

* [Overview](https://docs.ton.org/llms/foundations/whitepapers/overview/content.md)
* [The Open Network (TON)](https://docs.ton.org/llms/foundations/whitepapers/ton/content.md)
* [TON Virtual Machine (TON)](https://docs.ton.org/llms/foundations/whitepapers/tvm/content.md)
* [TON Blockchain](https://docs.ton.org/llms/foundations/whitepapers/tblkch/content.md)
* [Catchain consensus (legacy)](https://docs.ton.org/llms/foundations/whitepapers/catchain/content.md) — previous version of the consensus mechanism on TON