SAP Terminology
What Is a Client in SAP? Data Separation and Administration
Understand the SAP client concept, how client-dependent data is separated, how clients relate to users and customizing, and what administrators should check before copying or transporting data.
What a client is
An SAP client is a logically independent business environment within an SAP system. It has its own master data, transactional data, users, and configuration where the relevant objects are client-dependent. A client is identified by a three-digit numeric client number, such as 100 or 200.
The client is part of the application context selected during logon. The same SAP system can host several clients, allowing organizations to separate development, test, training, or business environments while sharing the underlying system infrastructure.
How client data is separated
SAP tables and application objects can be client-dependent or cross-client. Client-dependent records contain the client as part of their logical key, so users working in client 100 normally see the records belonging to that client. Cross-client objects apply across the system and require additional care during administration.
This arrangement provides logical data separation rather than a separate database server for every client. It supports multiple business environments in one system, but it does not replace authorization design, operational controls, or protection of sensitive data.
Client-dependent and cross-client objects
Common client-dependent content includes business partners or customers, vendors, materials, documents, and much of the application customizing. User and role administration also operates in a client context for the relevant user records.
The ABAP repository and several technical settings are cross-client. A change to a cross-client object can affect more than one client, so administrators should confirm the object scope before making changes in a productive system.
Client roles in a system landscape
A client often has an operational purpose such as development, quality assurance, training, or production. The number alone does not define that purpose; the system owner documents the role, permitted activities, interfaces, and refresh process for each client.
A client can also represent a company or business environment within a shared SAP system. The appropriate design depends on data ownership, legal or organizational separation, reporting requirements, integration boundaries, and the need for independent lifecycle management.
Users and logon clients
A user selects a client during SAP GUI logon. The same user ID can have different settings, authorizations, defaults, and validity in different clients because user administration is maintained in a client context.
When troubleshooting access, record the system ID, client number, user ID, logon language, and application server. Checking only the user ID without the client can lead to an incorrect diagnosis.
For practical user administration, see SAP user management in SU01. For login failures that occur after repeated incorrect passwords, see SAP login failure troubleshooting.
Customizing and transports
Client-dependent customizing is commonly maintained in a development client and moved through the system landscape with transport requests. The transport route, target client, and import sequence should be confirmed before a change is released.
Not every object follows the same transport behavior. Some settings are cross-client, some are client-dependent, and some require separate data loads or manual post-processing. Review the object scope and test the result in the target client.
A transport request is the mechanism used to organize and move many configuration and development changes.
Client copy and refresh operations
A client copy creates or refreshes client content according to the selected copy profile and system rules. Before starting one, confirm the source and target clients, available space, user impact, interface behavior, background jobs, and the treatment of application data.
A refresh can overwrite target-client data and can also leave integrations, logical system assignments, or environment-specific settings requiring follow-up. Freeze relevant business activity, document the rollback approach, and validate the result with application owners.
Operational checks
Use this checklist when investigating a client-related issue:
- Confirm the SAP system and client number shown in the session.
- Identify whether the affected object is client-dependent or cross-client.
- Check the user, role, and authorization context in the same client.
- Review recent transports, client copies, imports, or configuration changes.
- Confirm that background jobs and interfaces point to the intended client.
- Test the behavior with an approved diagnostic user and record the exact transaction or application step.
For concepts involving a unit of work and database consistency, see SAP logical unit of work terminology. For broader SAP platform vocabulary, see SAP terminology explained.