Software and Applications

Week of 2026-09-22 · Download .docx

Objectives

Compare SaaS, PWA, cloud sync, and web applications and describe their advantages.
Describe software installation methods including MSI, package managers, and winget.
Troubleshoot common software problems including missing DLLs and compatibility issues.
Compare software licensing models including open-source, freeware, shareware, and GPL.

Key terms

SaaS: Software as a Service — provider-hosted app accessed through a browser; no local install required.
Open-source: Software with publicly available source code that can be viewed, modified, and redistributed.
Freeware: Free to use but closed-source; source code is not provided.
Shareware: Try-before-you-buy model; free trial with features or time limited until a license is purchased.
GPL: GNU General Public License — copyleft license requiring derivatives to also be GPL-licensed.
Device driver: Software that translates OS commands into hardware-specific signals.
Firmware: Persistent software stored in non-volatile memory on a hardware device.
MSI: Windows Installer package format; supports Group Policy deployment in enterprise environments.
WSUS: Windows Server Update Services — centralized Microsoft update management for enterprise networks.
apt: Debian/Ubuntu package manager that downloads, installs, and resolves software dependencies.
winget: Microsoft's native Windows command-line package manager built into Windows 10/11.
Compatibility Mode: Windows feature that runs an application as if it were running on a previous OS version.
sfc /scannow: System File Checker — scans protected Windows files and replaces corrupted ones.
PWA: Progressive Web App — web app installable from a browser with offline capability via service workers.
DLL: Dynamic Link Library — shared code library loaded by applications at runtime.

The concept

Software is the set of instructions that tells hardware what to do. It is categorized into system software (OS, drivers, firmware) and application software (word processors, games, web browsers). The licensing model determines what users can legally do with the software.

Open-source licenses grant users the right to view, modify, and redistribute source code. The GPL (GNU General Public License) is copyleft: any product that incorporates GPL code and is distributed must itself be released under the GPL. Freeware is free to use but the source is not disclosed. Shareware lets you try before buying, with the full version unlocked after purchase. Public-domain software has no copyright restrictions.

Software installation methods vary by environment. On Windows, MSI packages contain a structured installation database that Group Policy can deploy silently across an enterprise. The built-in winget command-line tool installs apps from the Microsoft Store and other configured sources. WSUS lets IT approve and schedule Windows updates centrally before they reach endpoints. On Linux and macOS, package managers (apt, dnf, brew) download software and all its dependencies from curated repositories in a single command — no hunting for installer files.

Troubleshooting software problems follows a systematic approach. An application crash is best diagnosed through Event Viewer's Application log, which records error codes and exception details. A 'missing DLL' error means a required runtime library was not installed — the fix is to install the specific Visual C++ redistributable or other dependency. Windows Compatibility Mode can resolve issues with legacy applications that check the OS version and refuse to run on newer Windows. Running as Administrator resolves permission errors where a program needs to write to protected folders or registry keys. The sfc /scannow command verifies and restores corrupted OS system files.

Cloud-based software delivery has transformed how applications are used. SaaS (Software as a Service) applications like Microsoft 365 are hosted and maintained by the provider — users access them through a browser with no installation required. Updates deploy automatically server-side. Progressive Web Apps (PWAs) bridge web and native apps by using service workers to work offline and installable from the browser. Cloud sync services monitor a local folder and push changes to the cloud and other signed-in devices in near-real time.

Worked examples

Example 1: An older application used for data entry runs fine on Windows 7 but crashes immediately on Windows 11 with an error about an unsupported operating system. You right-click the executable, select Properties > Compatibility, check 'Run this program in compatibility mode for' and select Windows 7. The app launches successfully. This works because Compatibility Mode masks the current OS version from the application's version check.

Example 2: A technician needs to deploy a new accounting application to 200 Windows PCs. The application vendor provides an MSI file. The IT admin adds the MSI as a software package in Group Policy under Computer Configuration > Software Settings > Software Installation. On next login, all 200 PCs install the software silently without user interaction — demonstrating why MSI format is the enterprise deployment standard.

Common mistakes

Deleting the program folder instead of using Settings > Apps to uninstall — leaves registry entries and file associations that can cause issues.
Assuming freeware is open-source — freeware has no cost but the source code is not available.
Installing a 64-bit application on a 32-bit OS — it will fail; 64-bit apps require a 64-bit OS.
Using apt on a Red Hat/Fedora system — apt is Debian/Ubuntu only; Fedora uses dnf.
Ignoring Event Viewer after a crash and guessing at causes — always check the Application log first.

Self-check

Try each one before you look. A miss here costs nothing and tells you exactly what to reread.

1. Which license requires derivatives to also be released under the same license?

2. What is the correct tool to diagnose an application crash on Windows?

3. Which Windows tool is used for enterprise-wide silent software deployment using MSI packages?

4. A 'missing DLL' error most likely means:

5. What distinguishes SaaS from traditional installed software?

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