What is ERP? Meaning, modules and how it works
A plain explanation of enterprise resource planning: what each module does, how ERP differs from accounting software, where it can run and when a business needs one.
Last updated 21 October 2026
What is ERP?
ERP (enterprise resource planning) is business software that runs accounting, inventory, purchasing, sales, manufacturing and HR from one shared database. A sale entered once updates stock, the customer’s account and the ledgers together, so every team works from the same figures instead of reconciling separate spreadsheets and tools.
Where ERPStack is today
ERPStack is in development. It is not yet available to download or buy, and the features on this page are planned, not shipped.
Sign upWhat modules does an ERP include?
An ERP is made of modules that share one database. Most businesses start with two or three and add the rest as they grow.
| Module | What it handles | Example of the shared data at work |
|---|---|---|
| Finance and accounting | Ledgers, GST, receivables, payables, bank reconciliation, financial statements | A sales invoice posts to the customer’s account and the GST ledger at once |
| Inventory | Stock levels, warehouses, batches and serial numbers, transfers, valuation | A delivery reduces stock and updates its value in the books |
| Purchasing | Purchase requests, orders, goods receipt, supplier bills | Reorder levels raise a purchase request when stock runs low |
| Sales and CRM | Leads, quotes, sales orders, invoicing, customer history | A won quote becomes an order and then an invoice without re-typing |
| Manufacturing | Bills of materials, work orders, production planning, costing | A work order consumes raw material stock and adds finished goods |
| HR and payroll | Employee records, attendance, leave, payroll | Approved leave and attendance flow into the month’s salary |
| Projects | Tasks, timesheets, project costs and billing | Time logged on a project is billed to the client |
How is ERP different from accounting software?
Accounting software records the financial result of what happened. An ERP also runs the work that produces it: the purchase order, the stock movement, the production run. Standalone tools each do one job well but keep their own copy of the data.
| Accounting software | Standalone tools | ERP | |
|---|---|---|---|
| Scope | Books, GST, basic stock | One job each: CRM, inventory, payroll, billing | Accounting plus operations in one system |
| Data | One database for finance | A separate database per tool | One shared database |
| Re-entry | Operations data typed in from elsewhere | Exports and imports between tools | Entered once, used everywhere |
| Reporting | Financial reports | Per-tool reports | Reports across sales, stock, production and finance |
| Set-up effort | Low | Low per tool, rising with integrations | Higher upfront, lower to run once live |
| Suits | Trading or service businesses with simple stock | Teams that need one specialist function | Businesses with several teams working on the same orders and stock |
Should ERP run in the cloud, on-premise or self-hosted?
| Cloud (vendor-hosted) | On-premise | Self-hosted in your cloud account | |
|---|---|---|---|
| Where it runs | The vendor’s servers, used through a browser | A server in your office or data centre | A server you rent from a cloud provider |
| Who runs updates and backups | The vendor | You | You |
| Upfront cost | Low | Higher: hardware and set-up | Moderate: set-up, no hardware |
| Access from other sites | Built in | Needs VPN or remote access | Built in, if you set it up |
| Control over data location | Depends on the vendor | Full | Full, within your provider |
| Suits | Businesses without IT staff | Sites with unreliable internet or strict data rules | Teams with IT skills that want control |
For most small businesses without IT staff, cloud is the simpler start. Read more about cloud ERP for small business.
When does a business need an ERP?
The need usually shows up as friction between teams rather than a single failure:
- Stock in the books and stock on the shelf disagree every month.
- Orders, invoices and dispatches are typed into more than one place.
- Month-end close waits for spreadsheets from several people.
- You cannot see the true cost or margin of a product or order.
- A second branch, warehouse or GSTIN has made the current tools creak.
- Owners make decisions from figures that are already out of date.
If two or more of these sound familiar, compare an ERP with the cost of the workarounds you run today.
How does ERP implementation work?
- Scope. List the processes and modules you need first, and the reports you want out.
- Choose. Shortlist systems, see them run your real scenarios, and check data export and support.
- Configure. Set up the chart of accounts, tax, items, warehouses, approval flows and users.
- Migrate data. Bring over opening balances, customers, suppliers, items and stock.
- Test and train. Run a full order-to-cash and procure-to-pay cycle before go-live.
- Go live. Switch at a period start, such as the beginning of a month or quarter, and keep support close for the first close.
Cost depends on modules, users, data and how much you customise. For an estimate based on your own scope, use Perimattic’s ERP implementation calculator.
What is ERPStack?
ERPStack is an ERP for Indian small and mid-sized businesses that Perimattic is building. What we plan:
- Accounting with GST billing, e-invoicing and e-way bills as the starting point.
- Inventory, purchasing and sales working from the same records.
- Manufacturing with bills of materials and work orders.
- HR, attendance, leave and payroll alongside.
- A vendor-hosted cloud option and a self-hosted option.
Status: ERPStack is in development and none of this is available to use yet. Sign up to tell us which modules you need first.
Go deeper on ERP
ERP, answered
What is the full form of ERP?
ERP stands for enterprise resource planning. Despite the word “enterprise”, ERP is not only for large companies: small and mid-sized businesses use it once their accounting, stock and sales records need to stay in step without manual re-entry.
Is accounting software an ERP?
Not on its own. Accounting software covers books, GST and often basic inventory well, and many small businesses run on it for years. An ERP goes further, adding purchasing workflows, manufacturing, CRM and HR in the same database. Whether you need that depends on how many separate tools and spreadsheets you are keeping in step today.
How long does ERP implementation take?
It depends on the number of modules, users, sites and how much data you migrate. A small business taking accounting and inventory first moves much faster than a manufacturer adding production planning across plants. Starting with a few modules and adding more later is the lower-risk path.
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