Begin with the computer
A computer is a machine that receives information, follows instructions, produces results and may store information for later.
Input → Processing → Output
↓
Storage
When you type a message, the keyboard provides input. The computer processes the characters, the screen displays output and the messaging application stores the conversation.
Hardware and software
Hardware is the physical equipment: processor, memory, disk, keyboard and screen.
Software is the organized collection of instructions, data, configuration and supporting components that makes the hardware perform useful work.
| Term | Simple meaning | Example |
|---|---|---|
| Code | Instructions written by a person | A rule that calculates a total |
| Program | Instructions prepared for execution | A command-line calculator |
| Application | Software designed for users | A mobile banking application |
| System | Connected software, data, infrastructure and people | A university information system |
Essential vocabulary
These words will appear throughout the course:
- Source code: instructions written by people in a programming language and saved in files
- Runtime: the environment that executes a program and provides what it needs while running
- Configuration: settings that change how software behaves without changing its main instructions
- Infrastructure: the computers, networks and services that allow software to operate
- Interface: the place where a person or another system interacts with software
You do not need to memorize these definitions now. Return to them whenever a term appears later.
Code is only one part
Imagine an attendance application. A button labeled “Absent” is not the whole software.
The system must also know:
- which teacher is connected
- which class is active
- which students belong to it
- when attendance may be changed
- where the records are stored
- who can see or correct them
- what happens if the network fails
Those rules, data, permissions and operating conditions are part of the software system.
Activity: see the complete system
Choose an application you use. Complete this table on paper:
| Question | Your answer |
|---|---|
| Who uses it? | |
| What information enters the system? | |
| What result does it produce? | |
| What information does it store? | |
| What could go wrong? | |
| Who maintains it? |
Check your understanding
Statement: “If the code works on the developer’s computer, the software is finished.”
False. The software may still fail for real users because of missing data, unclear rules, security problems, different environments or unavailable infrastructure. Working code is necessary, but it is not enough.
Key idea
Software engineering is the work of understanding a problem and building a complete, reliable system that solves it. Programming is one part of that work.
What you learned
- A computer transforms inputs into outputs by following instructions.
- Hardware is physical equipment, while software organizes useful behavior.
- Code, programs, applications and systems describe different levels of a solution.
- Working code alone does not guarantee useful or reliable software.
Knowledge check
- Is a source-code file already a complete software system?
- Name the four elements in the input-processing-output model.
- Why does an attendance system need rules in addition to an interface?
- No. It becomes part of a system when combined with execution, data, rules, interfaces and operational support.
- Input, processing, output and storage.
- The interface captures actions, but rules decide who may act, which data is valid and how exceptional cases are handled.