Software

1. Quick Summary

• Software = programs that control hardware; it splits into system software (runs the machine) and application software (runs the user's tasks).
• System software includes the operating system, utilities, compilers, linkers, and device drivers.
• Utility software maintains, enhances or repairs a system — e.g. defragmentation, compression, encryption, task manager.
• The OS manages memory, the processor, inputs/outputs, files, security, and print spooling — and it's either single-user or a network OS.
• Application software comes in many flavours: word processing, spreadsheets, DTP, databases, web authoring, image/sound editing, presentation, control, and project management software.
• Software licences are either free/open source (editable, community-supported) or proprietary (paid, professionally supported).
• Communication software (browsers, email, social media, SMS/MMS, instant messaging) lets people exchange data remotely.
• Software gets updated to fix bugs, improve compatibility/performance, add features — but updating (and NOT updating) both carry risks.

2. System vs Application Software

Think of a computer system as having two halves: the hardware (the physical stuff you can touch — CPU, RAM, hard disk) and the software (the invisible instructions that tell the hardware what to do). You cannot touch software — it's just data stored on the computer.

Software itself then splits into two categories, and this split is the single most important idea in the whole chapter:

Here's a simple way to picture the hierarchy from the chapter's own diagram:

Why does the split matter?

Without system software, you have no starting point for giving the computer any instructions at all — it's the platform everything else sits on top of. Application software is then installed on top of the system software, and the user chooses which apps to install based on what they actually need to do (e.g. an accountant needs a spreadsheet; a graphic designer needs image editing software).

System software's essential jobs

• Compilers — translate high-level programming languages into machine code the CPU can execute.