Operating System, Application and Utility Software
Senior 3 · ICT
Operating System, Application and Utility Software
Lesson 4 of 5
25 min
Habimana's aunt needs a criminal record certificate for a job application. She does not queue at an office. On her phone she opens IremboGov, applies, pays with mobile money and later downloads the certificate. Two kinds of software made that possible: the application software she used, and the operating system on her phone that the application relied on for the screen, the network and the camera. This lesson sorts application software into categories, shows how applications work with the operating system, and walks you through Irembo, the Government of Rwanda's online services platform.
Definition
Application software (an app): a program that helps the user carry out a particular task, such as writing a letter, editing a photo or applying for a government service. It needs an operating system to run.
Software suite: a set of applications sold or shared together, with a common look and the ability to share data. Example: Microsoft 365 (Word, Excel, PowerPoint, Outlook) or LibreOffice (Writer, Calc, Impress, Base).
| Category | Main task | Examples |
|---|---|---|
| Word processing | Creating and formatting text documents | Microsoft Word, LibreOffice Writer, Google Docs |
| Spreadsheet | Calculating with numbers in rows and columns; charts | Microsoft Excel, LibreOffice Calc |
| Presentation | Making slide shows | Microsoft PowerPoint, LibreOffice Impress |
| Database | Storing, searching and reporting on large sets of records | Microsoft Access, LibreOffice Base |
| Desktop publishing | Laying out posters, newsletters and magazines | Microsoft Publisher, Scribus |
| Graphics and multimedia | Drawing, editing photos, sound and video | GIMP, Inkscape, Audacity, VLC media player |
| Web browser | Opening websites and web applications | Microsoft Edge, Google Chrome, Mozilla Firefox |
| Communication | Email, messaging and video calls | Outlook, Thunderbird, WhatsApp, Zoom |
| Education and programming | Learning and making programs | Scratch, a typing tutor, a dictionary app |
| Specialised (custom-made) | One organisation's own work | A hospital's patient-records system; a school's marks system; IremboGov |
Applications are also grouped by how they are made. Off-the-shelf (general-purpose) software is made for millions of users and bought or downloaded ready to use. Custom-made (bespoke) software is written for one organisation's needs: it fits that work exactly, but costs more and takes longer to build.
And by where they run:
| Kind | How you get it | Example |
|---|---|---|
| Desktop application | Installed on the computer's drive | LibreOffice Writer |
| Mobile app | Installed from an app store (Google Play, App Store) | IremboApp |
| Web application | Nothing to install: it runs inside a web browser | irembo.gov.rw; Google Docs |
An application does not control the hardware itself. Whenever it needs memory, processor time, a file, the screen, the network or a printer, it asks the operating system through an application programming interface (API), and the OS does the job.
Figure 1. Saving a file. The application only asks; the operating system, through its file system and the drive's driver, does the writing.
This explains three things you will notice:
.exe file) will not install on Android, and an Android app (.apk) will not install on Windows.Definition
Application programming interface (API): a set of ready-made functions and rules through which one program asks another, such as the operating system, to do something for it. Example: a word processor calls the Windows API to show the Save dialog.
System requirements: the minimum hardware and operating system that a program needs in order to install and run properly.
Worked example 1: will it install?
| Item | The program needs | The lab computer has | OK? |
|---|---|---|---|
| Operating system | Windows 10 or later, 64-bit | Windows 11, 64-bit | yes |
| Memory (RAM) | 4 GB | 8 GB | yes |
| Free storage | 2 GB | 1.2 GB | no |
The computer is short of GB of free space. Answer: not yet. Free at least 0.8 GB, more for safety, with Disk Cleanup or by removing unused programs (Lesson 3), then install.
IremboGov is the Government of Rwanda's platform for applying for public services online, on the website irembo.gov.rw or in the IremboApp for phones. Instead of visiting several offices, a citizen applies, pays and receives many documents in one place. Irembo's help centre groups the services like this:
| Group | Examples of services |
|---|---|
| Family | Birth and marriage services, the certificate of being single |
| Identification | Applying for, correcting or replacing a national ID |
| Immigration and emigration | E-passports, visas and permits |
| Land | Land title transfer and title updates |
| Car and motor | Driving licences, vehicle inspection, traffic fines |
| Health | Community-based health insurance (mutuelle), yellow fever |
| Other services | Criminal record clearance certificate, diploma equivalency, museum booking |
On the website, click Sign up, enter a phone number or email address and a password, and click Create account. A one-time code (OTP) arrives by SMS or email; enter it and click Verify. Then open My Identification and verify your identity with a Rwandan national ID and the phone number registered to it. Irembo requires a strong password: at least 8 characters, with a number, a capital letter, a small letter and a special character. In the IremboApp the steps are similar: choose a language (Kinyarwanda, English or French), tap Sign Up, give your national ID and phone number, enter the OTP and set a password.
Figure 2. Using a paid service on IremboGov. Some services are free and stop after step 2.
*182*3*7*Bill ID#, or accept a pop-up on the phone), Airtel Money (*182*4*5*1*Bill ID#), several banks, or a Visa, Mastercard or American Express card.Definition
Bill ID (billing number): the unique number, starting with 88, that IremboGov gives an application for a paid service. It is used to make the payment and to find the application again.
One-time password (OTP): a code, valid for a short time and for one use only, sent to your phone or email to prove that you own them.
Worked example 2: paying with a USSD code
Mutesi's mother applies for a service and receives Bill ID 880123456789 (an illustrative number). She has MTN Mobile Money. What does she dial?
*182*3*7* + Bill ID + #.*182*3*7*880123456789#.With Airtel Money she would dial *182*4*5*1*880123456789#. If she waits too long and the Bill ID expires, she must apply again.
Warning
Stay safe on government services. Type irembo.gov.rw yourself and check the address bar before you log in; a look-alike website can steal passwords. Never tell anyone your OTP, your Irembo password or your mobile money PIN, even someone who says they are helping you. Pay only with a Bill ID that you received from IremboGov.
GCFLearnFree (LearnFree): Computer Basics: Understanding Applications (under 2 minutes). Watch for the difference between desktop applications and mobile apps, and for the kinds of application it names; add one example to each row of the categories table above.
Tip
Exam hook: task, then example. When asked for categories of application software, give the category, its task and a named example: "Spreadsheet: calculates with numbers and draws charts, e.g. Microsoft Excel." For "how applications interact with the OS", the key word is request: the application requests, the OS does.
A. Spot the operating system inside your applications
B. Explore IremboGov (no application needed)
irembo.gov.rw. Check that the address bar shows exactly that address.Practice
.apk). Can she install it on her Windows laptop? Explain..apk is for Android and will not install on Windows. She needs the Windows version of the program, if one exists.*182*4*5*1*880987654321#Sources and credits
This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.