Like the other major applications of Odoo such as CRM, Sales, E-commerce, Project and Timesheet applications, Invoicing and Accounting are built-in applications. They are integrated with other applications as accounting is the heart of any business application.
Accounting is an important part of any business, ten years ago the challenge was to integrate all the group of company's financial data into a single document, such as a Profit and Loss and Balance sheet. Today the challenge is how to integrate accounting with different applications, such as Marketing, E-commerce, Customer Relationships, Help Desk, other than the core applications, such as Sales, Inventory, and Manufacturing.
In Odoo the accounting application is divided into two different applications—Invoicing and Accounting and Finance. The Invoicing application takes care of the customer invoices...