a set of things working together as parts of a mechanism or an interconnecting network of a complex whole.

a set of principles or procedures according to which something is done; an organized scheme or method

A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole

A group of interconnected computers and the accessories and devices that work together to perform a computing task. This must include both the hardware and software. The term system is very ubiquitous and could be used in various form and context.

In general, any computer system must take an input, process the input and produce an output.

Computer network systems

Webserver

Web content management system

Etc , etc

Light effects

Sound effects

Scenery

Game AI

DBMS (RDBMS)

Tables

Content Management System.

A critical system is a system which must be highly reliable and retain this reliability as it evolves without incurring prohibitive costs. There are four types of critical systems:

In computer sub system or module, is an extension to a main program dedicated to a specific function.

An embedded system is a computer hardware with a specific software inside it designed for a specific function.

Class diagram

Use case

object diagram

many others

Requirements Analysis.

Design

Implementation

testing

Maintenance

Requirements Elicitation