What is ERP and how does an ERP system work?

ERP stands for Enterprise Resource Planning: a single central software system in which an organisation brings together its core business processes, from finance and purchasing to inventory, production and HR. Instead of separate packages that operate in isolation, everyone works within one ERP system on the same data. That sounds simple, but the impact on an organisation is significant: ERP touches almost every process and every department.

This page explains what ERP means, how it works, which types and modules exist, and what to pay attention to during selection and implementation.

What is ERP and what does it stand for?

ERP (Enterprise Resource Planning) is business software that brings an organisation's core processes together in one system. "Resource planning" refers to planning and managing resources: money, inventory, capacity, people and materials. "Enterprise" indicates that it concerns the whole organisation, not a single department.

The feature that sets ERP apart from separate software packages is the shared database. An invoice, a stock movement or a production order is recorded once and is then visible and usable throughout the entire system. That prevents duplicate work, conflicting figures and error-prone links between systems.

A brief history: from MRP to ERP

ERP did not appear overnight; it is the result of decades of development in manufacturing software.

• MRP (Material Requirements Planning), 1960s-70s: software that calculated which materials were needed and when, based on stock levels and production planning.
• MRP II (Manufacturing Resource Planning), 1980s: an extension that added capacity planning, finance and other manufacturing-related processes.
• ERP, 1990s to present: the scope broadened to the entire organisation, not just production but also purchasing, sales, HR, projects and finance in one system.

Where MRP and MRP II were mainly aimed at the shop floor, ERP is now just as relevant for service providers, wholesalers and project organisations as it is for manufacturers.

How does an ERP system work?

An ERP system consists of modules that each support a business process, but which all use the same underlying database. When purchasing places an order, finance immediately sees the commitment, inventory management sees the expected replenishment, and production can plan based on the expected delivery.

One source of truth

Because all departments work with the same data, one reliable source of truth emerges. Reports, dashboards and KPIs are based on current, consistent data instead of exported files that are manually combined afterwards.

Modular structure

Most ERP systems are modular: you activate only the components you need and expand as the organisation grows. Common modules include:

Module	What it supports
Finance / accounting	General ledger, invoicing, payments, reporting
Purchasing	Suppliers, orders, contracts
Inventory / logistics	Stock management, warehouse management, distribution
Production	Production planning, material requirements, work orders
HR	Personnel files, absence, payroll
Projects	Project planning, hours, project budgets
CRM link	Customer data, sales opportunities, aftersales

Not every ERP package offers all modules itself; some connect to specialised software, for example a separate CRM system for sales and customer contact.

Types of ERP

ERP systems differ in how they are hosted and in how closely they are tailored to a particular industry.

Cloud (SaaS), on-premise and hybrid

• Cloud / SaaS: the system runs at the vendor, you typically pay a subscription and updates are rolled out centrally. Lower entry threshold, less in-house management, but dependency on the vendor.
• On-premise: the system runs on your own servers. More control and customisation options, but also more in-house responsibility for management, security and updates.
• Hybrid: a combination, for example a cloud core with some on-premise linked components, often due to regulation or existing investments.

Two-tier ERP

With two-tier ERP, headquarters uses an extensive ERP system, while subsidiaries or branches work with a lighter, cheaper system that connects to the main system. This suits organisations with multiple locations or countries that do not need the same level of complexity everywhere.

Industry-specific versus generic

Generic ERP systems are broadly applicable and flexibly configurable; industry-specific systems are pre-configured for the processes of a sector, such as construction, wholesale or healthcare. Industry-specific packages usually require less customisation, but offer less freedom outside the standard processes of that sector.

Advantages and disadvantages of ERP

Advantages

• One central, reliable source of data instead of separate systems and spreadsheets
• More efficient processes because departments no longer work in isolation
• Better organisational overview through real-time reporting and dashboards
• Scalability: adding modules as the organisation grows
• Less manual work and fewer error-prone handovers between systems

Disadvantages

• High initial investment in licences, implementation and possibly customisation
• Implementation projects are often lengthy and require significant internal capacity
• Changes to ways of working can meet resistance from employees
• A poorly chosen or poorly configured system is difficult and costly to reverse
• Dependency on the vendor, particularly with cloud solutions

In short: ERP delivers overview and efficiency, but requires a serious investment of money, time and change management.

When do you need ERP — and when not?

Signals that an organisation is ready for ERP:

• Separate systems for accounting, inventory and sales that do not connect to each other
• A lot of manual retyping of data between spreadsheets and systems
• No up-to-date or reliable overview of stock, revenue or capacity
• Growing complexity due to multiple locations, product lines or currencies
• Reports that take a lot of time and need to be checked afterwards

ERP is less obvious when an organisation is small, has few interconnected processes, or manages perfectly well with a few well-connected separate packages. Starting a full ERP project without that complexity often creates more overhead than benefit.

Selection and implementation process

Step-by-step plan

1. Map requirements and processes: which processes need support and what currently doesn't work well?
2. Package selection: compare vendors on functionality, industry fit, cost and scalability.
3. Choose an implementation partner: many ERP packages are implemented by certified partners rather than the vendor itself.
4. Configuration: translate processes into settings, roles and reports within the system.
5. Data migration: clean up existing data and transfer it to the new system.
6. Testing: functional testing by end users before the system goes live.
7. Training and change management: prepare employees for new ways of working.
8. Go-live and aftercare: go live in phases or all at once, with support during the initial period.

Data migration and change management

Data migration is often underestimated: old data contains duplicate customers, outdated items or inconsistent structures that cannot simply be transferred. Careful cleansing beforehand prevents errors from the old system carrying over into the new one.

Just as important is change management. ERP changes the way many employees work at the same time. Without clear communication, training and user involvement, acceptance of the system declines, even if the technology works perfectly well.

Cost components of an ERP project

The total cost of ERP consists of several components, the proportions of which vary strongly by organisation and package:

• Licences: usually per user or per module, one-off (on-premise) or recurring (SaaS)
• Implementation: configuration and guidance by an implementation partner
• Customisation: adjustments beyond standard functionality
• Management: hosting, updates and technical maintenance
• Training: educating employees and administrators

Specific amounts depend heavily on company size, number of users, chosen modules and degree of customisation; a reliable estimate only emerges from a quotation process with specific vendors.

Well-known ERP vendors

Without expressing a preference, these are some well-known names in the ERP market: SAP, Microsoft Dynamics 365, Oracle NetSuite, Odoo, Exact, AFAS and Unit4. These vendors differ in, among other things, target audience (from SME to multinational), industry focus and the degree of flexibility versus standardisation.

ERP versus CRM

ERP and CRM are regularly used interchangeably, but focus on different things. ERP is about internal business processes: finance, inventory, production and HR. CRM is about customer relationships: contacts, sales opportunities and customer communication. Many organisations use both side by side, with an integration so that customer data and order information align.

ERP and integrations with webshop and marketing

ERP systems rarely stand alone. For companies with a webshop, a link between ERP and the websites platform is valuable: stock, prices and orders then flow automatically, without manual reconciliation. A link with marketing systems can also be useful, for example to use customer segments from ERP in campaigns within online marketing or content marketing. When choosing an ERP system, it is therefore wise to also look at the available integrations and APIs.

Frequently asked questions

What does ERP stand for?

ERP stands for Enterprise Resource Planning: business software that brings together processes such as finance, purchasing, inventory, production and HR in one system with a single shared database.

What is the difference between ERP and CRM?

ERP supports internal business processes such as finance and inventory, while CRM focuses on customer relationships and sales. Many organisations use both systems side by side, linked to each other.

Is cloud ERP better than on-premise ERP?

Neither is inherently better; it depends on the situation. Cloud ERP requires less in-house management and has a lower entry threshold, while on-premise ERP offers more control and customisation options but requires more in-house capacity for management.

How long does an ERP implementation take?

This varies strongly by organisation, package and scope, from a few months for a compact implementation to longer for complex, multi-site projects. Careful preparation limits delays.

What does an ERP system cost?

Costs consist of licences, implementation, possibly customisation, management and training. Specific amounts vary strongly by organisation and can only be reliably estimated through a quotation process with specific vendors.

Does every company need ERP?

No. ERP is particularly valuable when complexity grows: multiple systems that don't connect, a lot of manual work, or insufficient insight into stock and figures. Smaller organisations with simple processes often manage fine with a few well-connected packages.