Open Source

Open Source is a software development and distribution model in which a program’s source code is available for viewing, studying, modifying, and distributing under the terms of the applicable license. The specific rights and restrictions are determined by the open-source license under which the project is released.

Open source allows developers to examine how a program works, adapt it to their needs, identify bugs, and contribute to the project’s development. However, open source does not mean that the software is free of copyright: it remains intellectual property and must be used in accordance with its license.

What Is Source Code?

Source code is the human-readable text of a program written by developers in a programming language. It contains instructions, algorithms, data structures, and other information that determines how an application works.

For many programming languages, source code is transformed into a form that a computer can execute before the program runs. Users of proprietary software typically receive a ready-to-use application but do not have access to its source code.

In open-source projects, the code is published and can be examined by other developers. Public repositories and version control systems such as Git are commonly used for this purpose.

Main Principles of Open Source

Making source code available is not enough for software to qualify as open source. The rights granted by the license are essential.

In general, open-source licenses allow users to:

• access the source code;
• use the software for various purposes;
• study how it works;
• modify the source code;
• create their own versions of the software;
• distribute the original or modified software in compliance with the license terms.

For example, a company can adapt an open-source library to its own requirements and pass the modified version on, as long as it complies with the license terms.

Requirements vary between licenses. For example, some allow open-source code to be incorporated into proprietary products, while others require the source code of derivative versions to be made available under compatible terms when they are distributed.

Open Source and Free Software

Open source is not synonymous with software that is free of charge. The defining characteristic of open-source software is not its price but access to the source code and the rights granted by its license.

Open-source software can be distributed free of charge or sold. Companies can also generate revenue from technical support, cloud services, implementation, development of additional features, and other services.

At the same time, freeware is not necessarily open source. A developer may allow users to use an application at no cost while keeping its source code closed and prohibiting modification or redistribution.

Open Source vs. Proprietary Software

Proprietary software is distributed under terms established by the copyright holder and generally does not provide users with access to the source code or the right to freely modify the software.

The main differences can be summarized as follows:

• Open Source — the source code is available, and the license grants rights to use, study, modify, and distribute it.
• Proprietary software — the source code is generally closed, while use and modification are restricted by the copyright holder’s license.
• Freeware — the software is available free of charge, but its source code may remain closed.
• Source-available software — the source code can be viewed, but the license may impose restrictions that prevent the software from meeting open-source criteria.

For example, a vendor may publish its product’s code in a public repository while prohibiting commercial use by third parties — such software is source-available rather than open source.

Therefore, publishing source code alone does not make a project open-source software.

Open-Source Licenses

The terms under which open-source software can be used are defined by its license. Open-source licenses are commonly divided into two broad groups.

Permissive licenses impose relatively few restrictions on the use and distribution of code. Examples include:

• MIT License;
• BSD licenses;
• Apache License 2.0.

For example, code released under the MIT License can be used in a commercial product provided that the copyright notice and license text are retained.

These licenses generally allow code to be used in commercial and proprietary products as long as the applicable requirements are met.

Copyleft licenses require derivative works to remain open under certain conditions. The best-known example is the GNU General Public License (GPL).

The terms of each license should be reviewed individually: different licenses impose different requirements regarding distribution, attribution, publication of modifications, and compatibility with other code.

How Open-Source Projects Are Developed

An open-source project can be developed by an individual developer, a community, a nonprofit organization, or a commercial company.

The code is typically stored in a version control repository. Contributors can report bugs, propose changes, create documentation, and test new versions.

A typical development process may include the following steps:

• A developer creates a copy of the project or a separate branch.
• The developer makes changes to the source code.
• The developer submits a proposal to incorporate the changes into the main project.
• Project maintainers review the code.
• After review, the changes are accepted or returned for further revision.

For example, a developer can submit a bug fix as a pull request, which the maintainers review before it is merged into the main version.

The ability to view the code does not mean that any user can directly modify the official version of the project. The project’s maintainers and governance model determine how contributions are accepted.

Examples of Open-Source Software

Open-source software is used in virtually every area of IT. Well-known examples include:

• Linux kernel — the kernel of Linux operating systems;
• Kubernetes — a container orchestration platform;
• PostgreSQL — a database management system;
• Apache HTTP Server — a web server;
• Nginx — a web server and reverse proxy with an open-source version;
• Git — a distributed version control system;
• LibreOffice — an office productivity suite;
• Blender — software for creating 3D graphics.

For example, a significant share of the internet’s server infrastructure runs on a combination of Linux, Nginx, and PostgreSQL — all three are open-source projects.

A large number of commercial products and cloud services are also built using open-source components.

Advantages of Open Source

The open-source development model can provide users and organizations with a number of advantages:

• the ability to examine and audit source code;
• the ability to adapt software to specific requirements;
• reduced dependence on a single vendor or developer;
• the ability to fix bugs independently or commission custom development;
• community participation in project development;
• the ability to integrate open-source components into proprietary solutions;
• transparency of the software mechanisms being used.

For example, a company can develop a feature it needs itself instead of waiting for a vendor’s roadmap.

However, access to source code alone does not guarantee software quality, security, or active project development.

Limitations and Risks of Open Source

Open-source projects vary considerably in maturity, documentation quality, and developer activity. Some are supported by large companies and extensive communities, while others effectively depend on only a few developers.

When using open-source software, it is important to consider:

• the availability of regular security updates;
• developer and community activity;
• documentation quality;
• compatibility with existing infrastructure;
• license terms;
• availability of professional technical support;
• risks associated with third-party dependencies.

For example, a barely maintained library embedded deep in an application can become a security risk once vulnerabilities stop being fixed.

For enterprise infrastructure, open-source software should therefore be evaluated not only in terms of functionality but also based on the project’s lifecycle, security, and long-term support options.

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