ERP and accounting systems are the software in which a company keeps its orders, stock, purchases, invoices and accounts, in one agreed database. This database is the company's system of record. When two teams disagree about a number, the figure in this system decides. It is the software a company changes least often, because almost everything else depends on it.
There are three kinds, sorted by the size of the customer.
Large and mid-sized companies run an enterprise resource planning (ERP) suite. ERP is one suite in which sales, the warehouse, purchasing and finance read and write the same records. The suite is sold in modules, such as sales, inventory, purchasing, production and finance, and the company switches on the modules it needs.
Some trades need features that a general suite does not have. A food maker must track every batch and its expiry date. A consultancy bills its clients by the hour, project by project. Such businesses often buy an industry-specific ERP, built for one trade. Once it is installed, such software is rarely removed.
A small shop needs something simpler. Small business accounting software makes the bill, records the stock and keeps the books, often on a phone. In India, it also prepares the figures for GST, the tax added to most goods and services.
Imagine a furniture maker in Jodhpur with 120 staff. Its ERP records an export order for 40 dining tables. It reserves the sheesham wood already in the store, and raises a purchase order for brass fittings. When the tables are shipped, it raises the invoice, and the same entries reach the accounts. At the end of the month, the finance team checks the ledger against the bank statement in financial close software, and closes the books.
Most new ERP and accounting software is sold as SaaS: it is rented by subscription and runs in the vendor's cloud. Older installations still run on the company's own servers. Moving from one ERP to another can take a large company one to three years. Before the new system goes live, teams test it with ERP testing tools.