Important Terms Related to System

System

Definition:
A system is a set of interrelated components working together to achieve a specific goal.

Example:
A School System includes students, teachers, exams, and administration — all working together for education.

Subsystem

Definition:
A subsystem is a smaller part of a system that performs a specific function within the overall system.

Example:
In a School System:

• Examination subsystem
• Library subsystem
• Attendance subsystem
  Each one handles a specific task.

Boundary

Definition:
The boundary defines what is inside the system and what is outside — i.e., the limits of the system.

Example:
In a payroll system, employee salary processing is inside the system, but government tax rules are outside.

Environment

Definition:
The environment refers to anything external that interacts with the system.

Example:
In a railway reservation system:

• Users
• Bank servers
• Train database
  All are part of the environment.

Interface

Definition:
An interface is a point where the system interacts with its environment or subsystems.

Example:

• A mobile app UI is an interface between the user and the booking system.
• The keyboard/mouse is an interface between you and the computer.

Input

Definition:
An input is any data or information that is entered into the system to be processed.

Example:
In an online exam system:

• Student ID
• Password
• Answers
  are all inputs.

Output

Definition:
The output is the result produced by the system after processing inputs.

Example:
In an online exam system:

• Marks
• Grades
• Pass/Fail report
  are the outputs.

Process

Definition:
A process is the operation that transforms input into output.

Example:
In a billing system:

• Adding items to a cart
• Calculating total
• Applying tax
  All are processes.

Feedback

Definition:
Feedback is the output that is sent back into the system to improve future performance.

Example:
In an e-learning app:

• Student feedback on a lesson can help redesign the content.

Control

Definition:
Control to rules, procedures, or mechanisms to guide the system.

Example:
In ATM software:

• You can’t withdraw more than ₹20,000 per day (a control rule).

System Flow

Definition:
System flow describes the movement of data and control through the system.

Example:
In a banking system:

1. Customer enters ATM PIN
2. System checks balance
3. If valid → proceeds to withdrawal
   This is the flow of data and decision.

System Analyst

Definition:
A System Analyst is a person who studies the system, gathers requirements, and helps design it.

Example:
If a college wants an ERP system, the system analyst interviews staff, students, and IT to build the right solution.

System Design

Definition:
System design is the process of defining architecture, modules, interfaces, and data for a system.

Example:
In a hospital management system:

• Patient module
• Doctor module
• Billing module
  All are part of system design.

Data Flow Diagram (DFD)

Definition:
A DFD shows how data moves through a system — what data comes in, how it’s processed, and what goes out.

Example:
In a Student Result System:

• Input: Marks
• Process: Calculate Total & Grade
• Output: Report Card
  All shown using DFD.

Entity

Definition:
An entity is a person, place, object, or event about which data is collected.

Example:
In a school system:

• Student
• Teacher
• Subject
  are all entities.

Data Dictionary

Definition:
A data dictionary defines all data elements used in the system (name, type, format, size).

Example:

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