docs(notes): add bank ledger and software documentation

Author: lzwjava

notes/2025-03-25-bank-ledger-en.md

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+---
+title: Bank Ledger
+lang: en
+layout: post
+audio: false
+translated: false
+generated: true
+---
+
+A bank ledger is essentially the detailed record of all financial transactions that affect the bank’s accounts. It works as the backbone of the bank’s accounting system, ensuring that every movement of money—whether it’s a deposit, withdrawal, loan disbursement, or fee—is accurately recorded and balanced.
+
+### Key Components and How It Works
+
+1. **Double-Entry Bookkeeping**  
+   - **Debits and Credits:** Every transaction is recorded with at least two entries: a debit in one account and a corresponding credit in another. This system ensures that the books always balance, as the total debits equal the total credits.
+   - **Accuracy and Error Detection:** If the sums don’t match, it signals an error, prompting a review and correction.
+
+2. **Types of Accounts**  
+   - **Asset Accounts:** These include cash on hand, loans given, and other resources.
+   - **Liability Accounts:** These cover deposits made by customers, which the bank owes back.
+   - **Equity Accounts:** Represent the bank’s own capital and retained earnings.
+   - **Revenue and Expense Accounts:** Track the bank’s earnings from interest and fees as well as operational costs.
+
+3. **Transaction Recording Process**  
+   - **Entry of Transactions:** Every time money moves—such as when a customer deposits cash—the transaction is logged with details like the date, amount, and nature of the transaction.
+   - **Reconciliation:** At the end of a period (daily, monthly, quarterly), the ledger is reconciled to ensure that all accounts accurately reflect the bank’s financial status.
+   - **Audit Trail:** Detailed records provide a clear audit trail, which is essential for internal checks and regulatory compliance.
+
+4. **Digital and Automated Systems**  
+   - **Software Systems:** Modern banks use sophisticated software that automatically posts entries to the ledger, minimizes human error, and allows real-time monitoring.
+   - **Security and Integrity:** These systems are designed with strong controls to protect the integrity of the ledger, ensuring that records are both secure and tamper-proof.
+
+### Why It’s Important
+
+- **Regulatory Compliance:** Accurate ledgers help banks comply with financial regulations and provide transparency to regulators.
+- **Financial Health Monitoring:** The ledger is a critical tool for assessing the bank’s performance and financial stability.
+- **Decision Making:** Detailed financial records support strategic planning and operational decisions within the bank.
+
+In summary, the ledger in a bank is a critical tool that not only records every financial transaction with precision using a double-entry system but also ensures that the bank’s financial data is accurate, secure, and compliant with regulations.

notes/2025-03-25-bank-software-en.md

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+---
+title: Ledger Software Systems
+lang: en
+layout: post
+audio: false
+translated: false
+generated: true
+---
+
+Top banks employ a variety of sophisticated ledger software systems to manage their financial transactions and operations. Some of the prominent systems include:
+
+1. **Avaloq**: A Swiss-based company, Avaloq offers the Avaloq Banking Suite, a comprehensive core banking software used by over 450 clients, including HSBC, Barclays, and UBS. The suite manages customer information, transactions, and account balances, supporting various banking functions. citeturn0search12
+
+2. **Temenos**: Founded in 1993 and headquartered in Geneva, Temenos provides banking software systems to over 3,000 financial institutions in 145 countries. Its flagship product, Temenos Transact (formerly T24), is utilized by 41 of the top 50 banks worldwide for core banking operations. citeturn0search13
+
+3. **TCS BaNCS**: Developed by Tata Consultancy Services, TCS BaNCS is a core banking software suite encompassing functions like universal banking, payments, and wealth management. It has been implemented by major banks such as State Bank of India and National Bank of Kuwait. citeturn0search14
+
+4. **Finacle**: Created by Infosys in 1999, Finacle is a core banking software suite that automates banking processes and offers digital banking services. It is deployed by banks in over 100 countries, facilitating various banking operations. citeturn0search16
+
+5. **Murex**: Established in 1986, Murex provides the MX.3 platform, catering to trading, treasury, risk, and post-trade operations. Its clients include UBS, National Bank of Canada, and Bank of China, among others. citeturn0search17
+
+6. **Axoni**: An American technology company, Axoni develops blockchain software for financial institutions. Its distributed ledger system, Veris, is used by major financial companies like BlackRock, Goldman Sachs, and Citigroup for managing equity swap transactions. citeturn0search15
+
+Additionally, some banks are exploring or implementing distributed ledger technologies (DLT) to enhance their back-office operations. For instance, in 2017, Citi deployed a "blockchain-inspired" distributed ledger platform developed by Baton Systems to manage collateral and expedite settlement processes. citeturn0search1
+
+The choice of ledger software varies among banks based on factors such as size, operational complexity, regional presence, and specific business needs.