ERP (Enterprise Resource Planning)

The defining feature is the shared database, not the list of features. Plenty of tools do invoicing. What makes something an ERP is that issuing the invoice also reduces stock, updates the customer's balance and posts to the ledger, because all three live in the same place.

That is why companies usually describe the problem before they name the solution. They do not say they need ERP. They say reports take too long, or that sales and accounting disagree, or that nobody can say what is actually in the warehouse. Those are all symptoms of running separate systems that each hold a partial copy of the truth.

ERP has a reputation for being enterprise-only, and historically that was fair: early systems needed servers, consultants and a year. Cloud delivery changed the economics enough that a company of thirty people can now run one, usually starting with two or three modules rather than the whole suite.