What Is Source Code? (Definition, Uses, and Examples)

By Indeed Editorial Team

Published May 23, 2022

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

Programmers create websites, computer games, and applications by writing code. One of the most common types of code is source code, and most web development projects use it. If you're a computer programmer or simply interested in web development, learning more about source code can be helpful for your tech career. In this article, we answer the question "What is source code?", explain the structure of a source text, explore who typically uses source code and how they use it, discuss the different types of code, and offer two examples of what it may look like.

What is source code?

Learning the answer to the question "What is source code?" can help you learn more about computer programming. Source code is a group of instructions that a programmer writes using a programming language. Once a programmer writes a set of source code, they can later implement it in a website, application, or another type of computer program to give it instructions for how to function. For example, someone might write a line of source code that tells a website to respond in a certain way when a user clicks on a specific place on a web page, like a hyperlink.

Programmers typically write source code in a text-based program, such as a word processor, and then use a compiler to translate it into a format that computer programs can read. When source code undergoes this translation, it then becomes object code. Before translation, it's often easy to read and understand as it describes the function a programmer wants to add to a website or program. After translation, a programmer can store it on a computer for future reference, either in a database or on a hard drive. They can also print physical copies of their source code.

Related: Understanding the Difference Between Coding vs. Programming

Structure of a source text

Depending on the programming language you choose, your source code may contain the following elements:

  • Commands: All code needs a command to give instructions to the device reading it. For example, a command may be to print certain text to a device's screen.

  • Variables: A variable is a vacancy in the code that programmers can fill with information.

  • Comparisons: A comparison is an if-then scheme, meaning when one instruction happens, it triggers another one. For example, once the device prints a welcome message, it may then offer a welcome picture or video.

  • Loop: Programmers may include commands that repeat until reaching a certain value, making a loop. For example, a welcome message may continue to pop up until a user clicks anywhere on the website.

  • Comments: This is any information programmers or developers include that the program doesn't apply. It allows people to communicate with one another within the code.

Who uses source code?

Computer programmers use and write source code. They can develop and implement it into almost any type of application or program, depending on the company they work for and the kinds of projects they work on. They can also use a few different tools to create new source code, such as a visual programming tool, a text editor, or an integrated development environment.

While computer programmers often use source code by writing one set of code for small programs, they can also create multiple sets of source code for a single project if it's a large-scale program. In these cases, it might be necessary to use different types of programming languages that can facilitate complex instructions. Here are some of the most common computer programming languages that professionals can use to write source code:

  • C

  • C++

  • Java

  • JavaScript

  • Pascal

  • Python

  • BASIC

  • PHP

Related: Top Python Interview Questions

Common uses of source code

Here are four ways people typically use source code:

Communicate algorithms

Programmers can use source code to share algorithms with each other. Most programmers write source code in word processors or other text-based software, which allows them to print out physical copies of their code or save it as document files. They can then share these files with other interested programmers or programmers who want to implement a particular source code into one of their projects. They can also use printed source code in products, like instruction manuals or informational books, to teach others how to write code.

Related: 14 Computer Science Salaries and Jobs (With Common Duties)

Build the foundation of a website

Web developers and designers can use source code to create the foundation of new websites. It gives the website instructions to function properly and respond to user interactions, such as clicking on a new page. Programmers typically use a coding language called HTML to create a website's foundation. HTML is a markup language because it has its own code words for manipulating a document's content. For example, coders can easily bold a website's headers and italicize its content using HTML.

Educate new programmers

Source code is relatively easy to read, unlike more complex types of code such as machine code, for example. Source code typically includes words and common punctuation, like brackets and apostrophes. This makes it easy for new programmers to learn before moving on to more complicated codes. Some programmers even share their source code for other programmers to use in their software or website design, helping them save time.

Add a specific function to a program

Another very common use for source code is to add a specific function to a computer program, application, or website. Many technology professionals consider this the primary use for source code, as it can make a considerable difference in the functionality and appearance of programs in development. For example, if a programmer working on a video game wants a special screen to appear when players enter a new area of gameplay, they can add an instruction in the source code telling the program to display the screen after the player's avatar reaches a particular point in the game.

Related: Top 15 Careers in Programming (With Salaries and Job Duties)

What types of code are there?

Here are four other types of code:

Object code

For source code to function, a computer translates it into object code using a compiler. Object code is a set of instructions that a computer can understand at its lowest hardware level. Once the compiler creates the object code, it stores it in an object file so the machine can retrieve the instructions when necessary.

Bytecode

Bytecode is a type of object code that is processed by a virtual machine instead of a computer's processor. As bytecode is numeric, the virtual machine translates it into readable instructions. The most common coding language that uses bytecode is Java.

Machine code

All computers use machine code, which consists of digital binary numbers. This is a collection of zeros and ones that a computer's central processing unit (CPU) can read, allowing it to follow the code's instructions. As computers can't read source code, they translate it into machine code to understand it.

Microcode

Microcode is a set of small instructions that allow computers to perform short operations. You can find microcode between a computer's CPU and its instruction set architecture. Since microcode is within a computer's hardware, programmers can't alter it.

Source code examples

To help you understand source code better, consider the following examples of it in different coding languages:

Example 1

Consider this example of a simple line of source code and what it looks like in the C programming language:

<mark class="resolved" rel="comment_3444740"><em>#include < stdio.h > </em></mark>
<mark class="resolved" rel="comment_3444740"><em>int main( ) {
// printf("Welcome to my page") ;
}</em></mark>

This example shows a line of source code written using the computer programming language C. Many programmers use C or C++ when writing source code because it allows them to create simple lines of code that give basic instructions. In this example, the instruction the code gives appears as "print" and tells a program to print the text within the quotation marks and parentheses on the screen. Here, if a programmer were to compile the source code and implement it into a website, the respective page would display the text "Welcome to my page" on the screen.

Example 2

Here's the same example of source code in the Java language:

<em>class welcome </em><em>{
public static void main (String args[]) </em><em>{ </em>
<em>System.out.printIn("Welcome to my page");} </em>
<em>}</em>

Although this second example uses a different coding language, the result is the same. It gives devices the instruction to print the text "Welcome to my page," wherever the programmer puts it, like on a website's homepage. As both languages offer the same results in this example, programmers typically choose their preferred language. The main difference between the two is that C is a low-level, procedural language, while Java is a high-level, object-oriented programming language. This means Java is closer to the English language, making it easier to learn, understand, and use.

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