> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lerian.studio/llms.txt
> Use this file to discover all available pages before exploring further.

# Fundamentals: Core Banking series

> A new Fundamentals tab introduces the Core Banking series, explaining double-entry, building blocks, money movement, and how to design a ledger plan.

<Badge stroke icon="calendar-days" iconType="regular">June 10, 2026</Badge> <Badge stroke icon="file-code" iconType="regular">Documentation update</Badge> <Badge color="green" size="lg" stroke icon="circle-check" iconType="regular">No migration required</Badge>

## Affects

***

Anyone learning how Lerian's ledger works from first principles — including engineers, product teams, and implementation partners onboarding to Midaz. This is new conceptual content and does not change any runtime API behavior, endpoints, or payloads.

## What changed

***

A new **Fundamentals** tab has been added to the documentation, opening with the **Core Banking** series. The series builds the mental model needed to design and operate a ledger, progressing from concepts to a practical ledger plan:

* **What is core banking** — what a core banking ledger is and the role it plays.
* **Double-entry explained** — why every movement has balanced debits and credits.
* **Building blocks** — ledgers, accounts, portfolios, and assets, and how they fit together.
* **How money moves** — the mechanics of transactions across accounts.
* **Holders, accounts & aliases** — modeling who owns what and how accounts are referenced.
* **External accounts and reconciliation** — representing the outside world and keeping it in sync.
* **Routes and fees** — directing movements and applying fees.
* **Designing your ledger plan** — putting the building blocks together for a real setup.
* **Where to go next** — pointers into the rest of the documentation.

## Impact

***

This is a **documentation-only** update. There is no change to product behavior, API contracts, or configuration. No migration is required. The series is conceptual and product-agnostic, providing the foundation that the rest of the Midaz and Lerian documentation builds on.

## What you need to do

***

<Steps>
  <Step>
    Start at **What is core banking** in the Fundamentals tab to build the base mental model.
  </Step>

  <Step>
    Follow the series through to **Designing your ledger plan** before modeling your own ledger.
  </Step>

  <Step>
    Use **Where to go next** to jump into the relevant product documentation for implementation.
  </Step>
</Steps>

### Deadline

None. No action is required to keep your integration working.

### Why

To give new and existing readers a single, progressive path that explains core banking and double-entry concepts before they reach product-specific documentation.

## Resources

***

* [What is core banking?](/en/fundamentals/core-banking/what-is-core-banking)
* [The building blocks](/en/fundamentals/core-banking/building-blocks)
* [Designing your ledger plan](/en/fundamentals/core-banking/designing-your-ledger-plan)