What is Open Source Software? Explained with Examples

Last Updated: 13 mins By: ThemeGrill Author

Wondering what open source software is? Well, you can stop wondering because this article will show you everything you need to know. 

Basically, open-source software (OSS) have a source code that anyone can edit, modify, and redistribute. A great example of open source software that you might have heard of is WordPress. 

Like all open source software, the source code of WordPress is free for any interested developer to study and edit. Yes, you read it correctly, the source code of WordPress can be modified by any developer as long as they follow certain rules.

In this article, we’ll tell you all there is to know about it, including the main question – what is open source software. Just keep reading and you’ll find out.

Open Source Software (Overview) 

As mentioned above, open source software is any software where the original developer has made the source code publicly available for everyone to study, modify, and upgrade. You can further distribute the modified software as well.

The source code is released under a license by the developers of the software. This license is basically a set of guidelines on how you can access, modify, and redistribute the software.

Open Source Software

History of Open Source Software 

In 1983, Richard Stallman, a programmer from MIT, came up with the idea of ‘free software movement’. The main motive behind this thought was to provide ‘freedom’ to the programmers to study and modify the source code according to their needs. 

Two years later in 1985, the non-profit Free Software Foundation (FSF) was formed to protect the ideology of the free software movement. 

Later in 1997, Eric Raymond published ‘The Cathedral and the Bazaar’, which gave birth to the idea to rebrand the free software movement to highlight the business potential of sharing and collaborating on software source code. The new term ‘Open Source’ was chosen to name this idea. 

A year later, the Open Source Initiative (OSI), a non-profit organization, was founded in 1998 to protect the open source principles and encourage this new term. 

Open Source Initiative

To avoid the misunderstanding and debate between free software and open source, other terms such as FOSS (free and open source software) and FLOSS (free, libre, and open source software) can be used to describe the concept. 

Although both have the same idea, which is to provide freedom to the programmers to study and modify the source code. The only difference is between their principle and philosophy. 

What is Open Source Code? 

Open source code is the coding part of the software. Usually, the source codes aren’t seen by the end-users of the software/application. For developers, however, these codes are important if they want to edit and modify the applications.

The open source codes are made available to the public domain by the original developers of the software. Furthermore, other developers can collaborate to add, fix bugs, and modify the code as much as they want. 

Open Source License

For example, the source code of WordPress is free to download and modify. Any developer can modify, fix bugs, and improve the features of WordPress and its not owned by anyone.

What is an Open Source License? 

OSS usually comes with a distribution license. The license includes all the terms and conditions that define how a developer can use, add, modify, and most importantly distribute the software. 

When the source code is modified, the developer must inform what was altered and also which method was used. Additionally, according to the license’s terms, it can be decided whether to make modified software free or not. 

According to the Black Duck Knowledge base, some of the most popular open source software licenses used are as follows.

  1. MIT license
  2. GNU General Public License (GPL) 2.0
  3. Apache License 2.0 
  4. GNU General Public License (GPL) 3.0
  5. BSD License 2.0 

To sum up, open source software can be downloaded freely, and also the codes can be changed and modified. But, of course, there are certain rules and regulations you need to follow. Those rules depend on the type of software license. 

WordPress as an Open Source Software

Now, let us give you a complete explanation of what is open source software through WordPress. WordPress is a popular Content Management System (CMS). It’s distributed under the GNU General Public License (GPL). 

You can easily download the latest version of WordPress from the official repository. Once they download it, anyone can effortlessly make changes, add or tweak the code part as per their need. Also, they can freely distribute it under the same license. 

Is WordPress Free (of cost)?

Now let’s talk about the cost involved in WordPress. There’s a myth that since the source code is free to modify, everything else involving the software is totally free of cost. But, that might not be the case. 

Yes, it’s true that the WordPress software is totally free. Free to use on unlimited sites and fully free of cost. But, there’s more than the core WordPress software that you need to create a WordPress website

Let’s start with the basics. First, you need a WordPress theme on your site. A theme is the main design layout that controls the overall appearance of your site. For instance, Zakra is an excellent multipurpose theme and it displays your content beautifully.  

Zakra Theme

You can get Zakra themes for free. But if you need additional features, then you need to purchase its paid version. 

Next, you need plugins. Plugins are the tools to add extra functionalities to your site. If you wanted to add user registration and login forms, User registration plugin from WPEverest is great option.

User Registration Form

This plugin is also free, but advanced features are limited to the paid version.

Additionally, WordPress powered sites require a web host which is a paid service. Basically, hosting can be considered as buying a storage location on the web where you can place your site online. Plus, you need a domain name (unique name for your site). 

Furthermore, sometimes the programmers can also charge money to provide customer support. 

To conclude, you need many things  (a theme, plugins, hosting, and domain, customer support) that aren’t free of cost. Hence, it’s not free to make a WordPress website, even though the WordPress software itself is free. 

Open Source Software Code

So hopefully, you’ve understood that open source software is open for collaboration to make it even better. But, we cannot completely say that it’s FREE OF CHARGE

For additional information, you can check out our article Is WordPress Free, which talks about the hidden costs behind WordPress.

Difference Between OSS and Other Softwares

To provide you a better perspective of open source software, here are comparisons between open source software and other types of software.

Open Source Software Vs Proprietary Software 

The source code of proprietary software can be only and only modified by the original developer of the software. It’s not made publicly available for other developers to edit and modify. 

However, you can freely use the software/application. But, you can’t modify its features, functions according to your needs.  As a result, propriety software are also called closed-source software.

Perfect examples of proprietary software are Microsoft Office and Adobe Photoshop. You can use the application freely but, you can’t modify the source code and create a modified new version of these applications. 

Microsoft Office Logo

To conclude, only the creators of proprietary software have the authority to add, delete, modify, and distribute the source code. On the other hand, open source software can be modified by any interested developer.

Of course, they’ve still got to follow certain rules and guidelines when modifying open source software. Such as the modified source code should be released under the same license as the original code. Besides, the developers have to report what they’ve modified and also the method they used.

Open Source Software Vs Free Software 

The difference between open source software and free software can be considered negligible. Actually, the concept of open source was derived to eliminate the limitations of free software. Open source is a development philosophy that’s more business-oriented, while free software is a social and moral philosophy. 

According to the Free Software Foundation (FSF), free software should have these four pillars of freedom.

  • The freedom to deploy the software for any use case without any restriction. 
  • To study the software and modify it according to your needs. 
  • Freedom to redistribute the software.
  • To enhance the performance of the software and release it for the community’s benefit. You can do it for free or charge money. 

Similarly, according to the Open Source Initiative (OSI), open source software must have the following criteria. 

  • Free distribution of the software.
  • The source code should be available in the public domain.
  • It can be modified according to the programmer’s choice.
  • Redistributed in a format different from the original software. 
  • It shouldn’t restrict the usage of other software. 
  • The software shouldn’t discriminate against any person or group. 

Technically, free software came earlier than open source software. Although both have the same idea ( right to use, study, modify, and distribute), their objectives and philosophies are different. 

Advantages and Disadvantages of Open Source Software

Of course, open source software has positives as well as negatives. To give you a better idea, some of the advantages and disadvantages of open source software are shown below.


  • The first and foremost benefit is that its source code is free to modify and change. 
  • Best of all, it provides a great opportunity for all the new programmers to learn/study the codes and improve their skills. 
  • Since the developers can collaborate to improve the software, it can be more bug free and secure than proprietary software. 
  • Not to mention, its quality can be easily improved since the source code is passed around, tested, and fixed by a lot of people. 
  • Open source software are perfect for long term projects as it’s always available in the public domain. So, there’s little to no chance it’ll be outdated or discontinued. 
  • Also, open source software come with a built-in community that continuously modifies and improves the source code. 


  • Open source can be difficult for some beginners as it often lacks a user-friendly interface. Also, it can be hard to set up. 
  • Sometimes, open source can result in some unexpected costs while setting the software, training the users, and importing data. 
  • It rarely provides any warranty, liability, or protection. The consumers are solely responsible for maintaining compliance with legal obligations. 

Overall, we would say that open source is an advantage to the community. It’s a great concept for any programmer, even for beginners. They can study the source code, learn, and test their skills. 

1) WordPress 

As mentioned earlier, WordPress is a very popular open source software and the dominant Content Management System (CMS) in the market today. Originally created as just a blogging platform on 27 May 2003, it has grown into a powerful platform that can build any kind of website

WordPress What is Open Source Software

Curretly, WordPress powers over 38% of all websites on the internet and over 63% of the CMS market. The source code of WordPress is free to study and modify. However, the other parts of running a website such as themes, plugins, and hosting may cost you money. 

2) Mozilla Firefox 

Mozilla Firefox or simply Firefox, is an internet browser and a free open source software. Created in 2002 and officially released on November 9, 2004, Firefox instantly spread throughout the internet with 60 million downloads within nine months.

Mozilla Firefox Open Source Code

Today, Firefox is the third most popular browser and holds 3.77% of the worldwide browser market share. It’s available for Android, iOS, Windows, and Linux.

3) Drupal

Drupal is a content management system (CMS) and open source software just like WordPress. It’s released under the GNU General Public License. Anyone can download, install, and use it as per their need. 

Drupal Website Builder Open Source Software

It was created by two students from the University of Antwerp, Dries Buytaert and Hans Snijder in 2001. There are over half a million sites powered by Drupal today. 

If you want to know which is the better CMS. Then, read our article about WordPress Vs Drupal – which is a better CMS for your website

4) Linux Operating System 

Linux is one of the most customizable operating systems on the market. It’s also one of the most versatile open source software, and is used on everything, including smartphones, cars, internet servers, and even supercomputers!

Linux Operating System

Linux originated in 1991, by a Finnish student Linus Torvalds. It’s free and open source nature has ensured that Linux has the largest user-base out of all operating systems.

5) Joomla 

Joomla is an open source website building software that has been in the game for a while now. Originally released in 2005, it now powers 2% of the web and over 3% of the CMS market today. 

Joomla Open Source Software

It uses the GNU General Public License, just like many other options on this list. Hence, anyone is free to download, install, and make changes to the code. On top of that, it can be freely redistributed as well. 

Check out our article WordPress Vs Joomla – Which is the better CMS? for a better perspective about WordPress and Joomla.

Wrapping Up 

So now you should know what open source is and how it works. As you can see the open source source code is free to make changes and modify. As a result, it is a great platform for all the developers that are keen to learn and study more.

The great thing about them is that everyone is allowed to study the source code, fix bugs, and redistribute the software. There are a ton of most popular open source software, including WordPress, Joomla, Drupal, and Mozilla Firefox, to just name a few,

And that’s all for now! Hope now you have a better understanding of what open source software is. If you learned something new today, then why not share this article with your friends on social media. 

Lastly, follow us on Twitter and Facebook for future updates. And let us know which is your favorite open source software in the comment below.


ThemeGrill Author

We are a team of SEO copywriters and editors who work both individually and in the team. ThemeGrill author is where one of the editors here is working on one project personally. Write to us @themegrill_blog in Twitter.

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