Why Does Software Exist? The Story Behind Every App You Use

Software exists to let one general-purpose machine solve many different problems. Instead of rebuilding hardware whenever the task changes, we change the instructions. That separation between the machine and its program is the idea behind every app you use.

You unlock your phone, send a message, order food, watch a movie, or pay a bill online. Behind every one of those actions is software telling hardware what to do.

If you are beginning to learn programming, it is easy to think that software started with languages such as Python, Java, or JavaScript. If you have developed software for years, you may spend more time thinking about frameworks, cloud platforms, and AI than about software's original purpose.

But every developer should ask a more fundamental question at least once:

Why does software exist at all?

The answer takes us back to a time when a computer could not simply run another application.

Why software exists: the short answer

Software exists because changing instructions is far more practical than rebuilding hardware for every new problem.

Early electronic computers could perform calculations at remarkable speed, but preparing them for a different task could require engineers to change switches, cables, or plugboards. The breakthrough was to represent a program as information that a computer could store and execute.

That made a computer reusable:

• The hardware provides general computing capabilities.
• Software describes a particular task.
• Changing the software changes what the same machine can do.

This principle still powers laptops, phones, servers, cloud platforms, and AI systems.

Imagine a world before modern software

Imagine buying a laptop today. You install a web browser, then decide that you want to edit a photo.

Instead of downloading an application, someone tells you:

To do that, you need to open the laptop and reconnect several wires inside it.

That sounds absurd now, but it resembles how some early electronic computers were programmed.

During the 1940s, many machines were designed for a limited set of calculations. Changing the computation often meant manually reconfiguring the machine. Running a different job was not as simple as opening another application; preparation could take hours or longer.

The computer was not unintelligent. It simply had no stored set of alternative instructions to follow.

The real problem was flexibility

Early computers were expensive, powerful, and fast for their time. Their limitation was flexibility.

Imagine hiring an exceptionally capable employee but rebuilding part of their brain every time you assign a different task. That is close to what engineers faced when a computer's operation was tightly bound to its physical configuration.

The important realization was:

The machine should not have to change every time the problem changes. The instructions should change.

That distinction laid the foundation for modern software.

The stored-program concept changed computing

In 1945, John von Neumann's First Draft of a Report on the EDVAC described a computer design in which instructions and data could be held in memory. The report became an influential description of what is now called the stored-program concept.

The history deserves a small qualification: the idea should not be treated as the work of one person in isolation. Engineers including J. Presper Eckert and John Mauchly were developing related ideas around ENIAC and EDVAC, and historians continue to discuss how credit should be assigned. What matters technically is the shift from configuring a machine for one job to storing a program that the machine can execute.

With a stored program:

1. Instructions are represented as information.
2. The instructions are placed in memory.
3. The processor reads and executes them.
4. A different program gives the same hardware a different purpose.

The hardware stays largely the same. The instructions change.

The Computer History Museum's account of the stored program explains why storing instructions in memory became the basis of software used by computers ever since.

What exactly is software?

Software is an organized collection of instructions and related data that tells a computer how to perform a task.

That description applies to:

• Web browsers
• Document editors
• Messaging applications
• Music and video services
• Banking systems
• Operating systems
• Games
• AI assistants

Every one of these systems eventually becomes instructions that hardware can execute.

Without software, hardware has potential but no useful direction. A computer without software is like a library full of books written in a language nobody can read: the capability is present, but the instructions that make it useful are missing.

What does a processor understand?

A processor does not directly understand commands such as open, save, log in, or search.

At the hardware level, a program becomes machine instructions that perform small operations, including:

• Reading data from memory
• Writing data to memory
• Adding numbers
• Comparing values
• Jumping to another instruction

These operations are encoded as binary patterns. Writing large applications directly in machine code would be slow and error-prone for humans, which is why programming languages and translation tools exist.

Why programming languages were invented

Suppose you want to calculate a total in JavaScript:

const total = price + tax;

This statement is compact, readable, and meaningful to a developer. A processor cannot execute JavaScript source code directly, so the code must be translated into operations the hardware understands.

Depending on the language and runtime, that work may involve a compiler, an interpreter, just-in-time compilation, or a combination of techniques.

Programming languages give humans a practical way to express algorithms, data structures, and system behavior. They let us focus on solving a problem instead of controlling individual electrical operations inside a processor.

Programming languages are therefore designed primarily for people. Translation tools bridge the gap between human-readable code and machine instructions.

One computer can become millions of tools

A laptop can become:

• A video editor
• A music studio
• A web server
• A game console
• A programming workstation
• A financial calculator
• A machine-learning platform

The CPU, memory, and storage do not need to be physically rebuilt for each role. Software transforms general-purpose hardware into a specialized tool.

This is one of the most powerful ideas in computing: a machine's purpose is not fixed when the machine is manufactured.

Where does the operating system fit?

Applications rarely control hardware directly. They usually request services from an operating system.

When you select Save in a document editor, a simplified path looks like this:

You
  ↓
Application
  ↓
Operating system
  ↓
Storage device

The operating system manages shared responsibilities such as:

• Memory allocation
• File systems
• Device communication
• Networking
• Security and permissions
• Process scheduling

Without an operating system, each application would need to manage many hardware details independently. Operating systems provide stable abstractions that make application development safer and more practical.

Why this still matters today

Modern developers work with technologies such as:

• Artificial intelligence
• Cloud computing
• Kubernetes
• Docker
• React
• Node.js
• Microservices

These technologies can seem far removed from early computers, but they still depend on the same fundamental relationship: general-purpose hardware executes stored instructions.

Whether you train an AI model, build a web application, or deploy services to the cloud, you are still solving problems by describing operations that computers can perform.

The scale has changed. The principle has not.

Programming is more than learning a language

One of the biggest misconceptions about programming is that it is mainly about learning syntax.

Programming is about understanding a problem and expressing a reliable solution. A language is one way to communicate that solution to a computer.

Instead of beginning with only this question:

Which programming language should I learn?

It is useful to ask:

What problem am I trying to solve, and what constraints shape the solution?

The choice of language, framework, and platform should follow from that understanding.

Final thoughts

Software was created so that computers could solve different problems without being physically rebuilt for every task.

The stored-program idea transformed computers from narrowly configured calculators into general-purpose machines. Every app you use, website you visit, game you play, and AI tool you interact with builds on that separation between hardware and instructions.

When you write a line of code, you participate in an idea that has evolved for decades:

Describe a problem clearly enough that a machine can help solve it.

Languages, frameworks, libraries, cloud platforms, and AI systems are layers built on top of that foundation.

Continue learning

This article answers why software exists. The next questions in this fundamentals series will explore how software works:

1. How does a computer actually run your code?
   From source code to machine instructions and execution inside the CPU.
2. What is an operating system, and why do applications need one?
   How an operating system manages hardware and provides services to programs.
3. What is a programming language?
   Compilers, interpreters, runtimes, and the translation from code to instructions.
4. How does the internet work?
   What happens between selecting a link and receiving a webpage.
5. How did software evolve from desktop programs to cloud services?
   The architectural changes that made software globally available.

You can find future articles in the software technology notes.

References and further reading

• John von Neumann, First Draft of a Report on the EDVAC, Moore School of Electrical Engineering, University of Pennsylvania, 1945. Smithsonian Libraries and Archives.
• Computer History Museum, The Stored Program.
• Computer History Museum, Programming the ENIAC: An Example of Why Computer History Is Hard.
• Andrew S. Tanenbaum and Todd Austin, Structured Computer Organization.
• David A. Patterson and John L. Hennessy, Computer Organization and Design.