Source code is written by programmers and is the foundation of any computer program. A programmer’s source code are instructions that guide the program’s execution and the process of writing source code is commonly referred to as “coding” or “programming.” Programmers write source code in a computer programming language (such as C++ or Python), so it appears in a human-readable text format.

A programmer can use a simple text editor to write the source code or use more sophisticated tools such as an integrated development environment (IDE). An IDE can improve a programmer’s workflow syntax by highlighting, auto-completing statements and debugging the source code.

A program’s source code can all be stored in a single file, but for larger programs, it’s usually beneficial to organize the source code into different sections in multiple files. This organization can help the programmer break the software down into more easily manageable chunks.

Interestingly, source code does not have to be digitally stored in a file of some sort. It can also be stored, for example, as printed text in a book of code snippets.


Source Code Example 

One of the simplest programs out there, and one that’s familiar to almost anyone with experience in programming is the “Hello, World!” program, which simply outputs (or displays) the message “Hello, World!” when executed.

We often use a “Hello, World!” program when teaching; it is typically the first thing a student learns when studying programming.

As an example here is a “Hello, World!” program in Python:

print("Hello, World!")

And here is one version of it in C++:

#include <iostream>

int main()
  std::cout << "Hello, World!\n";
  return 0;

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How Does Source Code Work?

Even if you have no experience in programming, you can easily understand the above examples of the “Hello, World!” program. When a programmer executes “Hello World,” the program executes line-by-line, top-to-bottom and left-to-right, just as if you were reading English. Even though the C++ “Hello, World!” program contains some syntax that might seem a little cryptic, it’s easy to deduce that the point of these examples is to output “Hello, World!”

Before you can actually execute the source code, you must translate (or compile) it to machine language that the computer can read. We do this with a program called a compiler. The translated code, known as object code, mainly consists of binary code (ones and zeroes) and, contrary to source code, cannot be easily understood by humans.

What Is Source Code and What Does It Do? | Video: Eye on Tech


Why Is Source Code Important?

The most important aspect of source code is that it provides the basic foundation for creating software. This feature of source code extends to other use cases as well. For example, source code allows for editing, customizing or developing the software further. These tasks would be impossible (or at least much harder) without the source code, even if you have the software running on your computer.

For all the reasons outlined above, a program’s source code makes it easier to develop similar software for other operating systems while also making it possible for multiple people (or even a large community) to co-develop software.


Alternatives to Writing Source Code

You might think that writing source code is the only way to create a program. However, there now exist other alternatives to programming as well.

These alternatives include visual programming tools that allow programmers to create software visually. Often this means the program uses block diagrams of some sort to display the program’s flow or behavior. Visual programming tools can be “no-code,” meaning that no coding is required (or even possible). Alternatively, visual programming can be “low-code,” meaning that, while writing source code may or may not be required, you can use it to expand the functionality of the visual programming tool. Examples of visual programming tools include LabVIEW, Simulink and Bubble.

You can also use cell-based programming tools, such as Excel or Google Sheets, wherein commands and instructions are written into the cells of a spreadsheet.

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