# Banking & Lending > How banks, credit unions, fintechs and lenders work, from the core and its ledgers to deposits, credit decisions, servicing and business spend. Banking is two promises and a balance sheet: a depositor is promised their money back on demand, up to a limit the government insures, and a borrower promises money back on a schedule, under rules that say what the lender had to disclose, how it decided, and what it may do when payments stop. The same dollar is recorded in several places that must agree to the cent (a fintech's ledger, a middleware subledger, a sponsor bank's core, the general ledger, the card processor and, if the bank fails, the FDIC's insurance determination), and a loan lives in the system that decided it, the servicer that bills it, the bureaus it is reported to and the investor who bought it. This book surveys how the industry does each piece, benchmarked across banks from JPMorgan Chase to community banks and credit unions, core vendors like Fiserv, FIS, Jack Henry, Temenos, Thought Machine, Mambu and 10x, sponsor banks and BaaS platforms, neobanks like Chime, SoFi and Cash App, lenders like Affirm, Upstart, Rocket and UWM, and spend platforms like Ramp, Brex and BILL, with no single company as the model, and how you'd build it, extending one core data model chapter by chapter. It reads in thirteen parts, plus a reference. The Business: the parties, how the money is made, the life of a deposit and of a loan, the core data model, the landscape, bank economics, charters and regulators, starting a bank, exams and call reports, and bank failures. The Core: core banking systems, posting, holds and balances, interest, APY and statements, product configuration, and core conversions. Deposits: deposit accounts and Truth in Savings, deposit insurance, funds availability, overdraft and fees, errors and disputes, dormancy and escheat, and legal process. Financial Crime: KYC and account opening, BSA/AML programs, sanctions screening, and account takeover and scams. Fintech and BaaS: neobanks, banking as a service, program ledgers and the Synapse lesson, sponsor bank oversight, earned wage access, credit builders, and open banking in the US, the UK and the EU. Lending Products: the lending business, credit cards, installment loans, auto lending, mortgages and home equity, student loans, and buy now, pay later. Business Lending: small business lending and the SBA, embedded lending, and commercial lending. Origination and Underwriting: origination, credit data and scores, decision engines, adverse action, fair lending, HMDA and 1071, model risk, APR and rate caps, mortgage disclosures, and closing and eNotes. Servicing and Collections: loan servicing, mortgage servicing and escrow, furnishing credit data, collections, and credit losses and CECL. Funding and Licensing: funding the book, the secondary mortgage market, and lender licensing and bank partnerships. Business Banking: startup and business accounts, sweeps and yield, and treasury management. Spend Management: the spend business, corporate cards, spend controls, expense policy, reimbursements, AP and procurement, business travel, and accounting sync. Running the Platform: architecture, digital banking, regulatory reporting, security and incident notice, AI, and metrics. Reference: a glossary of every term, grouped by part. ## Chapters - [The Banking & Lending Business](https://www.syntaqx.com/books/banking-and-lending/banking-business): How banks, credit unions, fintechs and lenders work: the parties, how the money is made, the life of a deposit and a loan, and the core data model. - [The Banking Landscape](https://www.syntaqx.com/books/banking-and-lending/banking-landscape): US banks by size, credit unions, core and digital banking vendors, sponsor banks and BaaS, neobanks, nonbank lenders, and who bought whom as of October 2026. - [Core Banking Systems](https://www.syntaqx.com/books/banking-and-lending/core-banking-systems): What a core does, the general ledger against its subledgers, the core vendors, hosted, in-house and cloud-native cores, and the systems around them. - [Posting, Holds & Balances](https://www.syntaqx.com/books/banking-and-lending/posting-holds-and-balances): Memo and hard posting, ledger, available and collected balances, holds and blocks, posting order and its litigation, end of day, and effective dates. - [Interest, APY & Statements](https://www.syntaqx.com/books/banking-and-lending/interest-and-statements): Day counts, balance methods, daily accrual against crediting, compounding, the Reg DD APY and APY earned formulas, statements, and 1099-INT and 1098. - [Products & Product Configuration](https://www.syntaqx.com/books/banking-and-lending/product-configuration): The product factory: rate tiers and promotions, fee schedules, versioning when terms change, change-in-terms notices and grandfathered accounts. - [Core Modernization & Conversions](https://www.syntaqx.com/books/banking-and-lending/core-modernization): Why cores are hard to replace: TSB 2018, Commonwealth Bank, JPMorgan on Thought Machine, big bang or progressive, conversion weekends, outsourcing risk. - [Deposit Accounts & Truth in Savings](https://www.syntaqx.com/books/banking-and-lending/deposit-accounts): Checking, savings, money market and CDs: Reg DD disclosures and advertising, Reg D after 2020, Reg Q's repeal, early withdrawal penalties and ownership types. - [Deposit Insurance](https://www.syntaqx.com/books/banking-and-lending/deposit-insurance): FDIC and NCUSIF coverage: ownership categories, the 2024 trust rule, pass-through and 330.5 records, the custodial proposal and computing insured amounts. - [Funds Availability](https://www.syntaqx.com/books/banking-and-lending/funds-availability): Regulation CC on the account: the next-day and second-day schedule, the 2025 amounts, exception holds and notices, new accounts, and how a core computes holds. - [Overdraft, NSF & Fees](https://www.syntaqx.com/books/banking-and-lending/overdraft-and-fees): Overdraft and NSF fees: the Reg E opt-in, APSN and the available balance, re-presentment, the 2024 CFPB rule and its 2025 repeal, and fee-free models. - [Banking & Lending Glossary](https://www.syntaqx.com/books/banking-and-lending/glossary): Every banking and lending term by part: the business, the core, deposits, financial crime, fintech, lending, underwriting, servicing, funding and spend.