Ledger

A Ledger contains all other objects, and is completely isolated from all other Ledgers.

You can't move Commodities between Accounts on different Ledgers.

Examples

Expense Reporting Software

For example, if your use-case is an expense reporting SaaS, you would generally have a Ledger per business, and a Ledger per individual user.

That would allow you to sync each individual user's personal credit cards into a separate Ledger, and to track pending and remitted expense reports in the business's Ledger.

Accounting Software

If you're writing accounting software for businesses, you'd need one Ledger per tenant of your software.