Closed Source (also known as Proprietary Software) refers to software whose source code is not publicly accessible and can only be viewed, modified, or distributed by the owner or developer. In contrast to Open Source software, where the source code is made publicly available, Closed Source software keeps the source code strictly confidential.

Characteristics of Closed Source Software:

1. Protected Source Code: The source code is not visible to the public. Only the developer or the company owning the software has access to it, preventing third parties from understanding the internal workings or making changes.

2. License Restrictions: Closed Source software is usually distributed under restrictive licenses that strictly regulate usage, modification, and redistribution. Users are only allowed to use the software within the terms set by the license.

3. Access Restrictions: Only authorized developers or teams within the company have permission to modify the code or add new features.

4. Commercial Use: Closed Source software is often offered as a commercial product. Users typically need to purchase a license or subscribe to use the software. Common examples include Microsoft Office and Adobe Photoshop.

5. Lower Transparency: Users cannot verify the code for vulnerabilities or hidden features (e.g., backdoors). This can be a concern if security and trust are important factors.

Advantages of Closed Source Software:

1. Protection of Intellectual Property: Companies protect their source code to prevent others from copying their business logic, algorithms, or special implementations.
2. Stability and Support: Since the developer has full control over the code, quality assurance is typically more stringent. Additionally, many Closed Source vendors offer robust technical support and regular updates.
3. Lower Risk of Code Manipulation: Since third parties have no access, there’s a reduced risk of unwanted code changes or the introduction of vulnerabilities from external sources.

Disadvantages of Closed Source Software:

1. No Customization Options: Users cannot customize the software to their specific needs or fix bugs independently, as they lack access to the source code.
2. Costs: Closed Source software often involves licensing fees or subscription costs, which can be expensive for businesses.
3. Dependence on the Vendor: Users rely entirely on the vendor to fix bugs, patch security issues, or add new features.

Examples of Closed Source Software:

Some well-known Closed Source programs and platforms include:

• Microsoft Windows: The operating system is Closed Source, and its code is owned by Microsoft.
• Adobe Creative Suite: Photoshop, Illustrator, and other Adobe products are proprietary.
• Apple iOS and macOS: These operating systems are Closed Source, meaning users can only use the officially provided versions.
• Proprietary Databases like Oracle Database: These are Closed Source and do not allow access to the internal code.

Difference Between Open Source and Closed Source:

• Open Source: The source code is freely available, and anyone can view, modify, and distribute it (under specific conditions depending on the license).
• Closed Source: The source code is not accessible, and usage and distribution are heavily restricted.

Summary:

Closed Source software is proprietary software whose source code is not publicly available. It is typically developed and offered commercially by companies. Users can use the software, but they cannot view or modify the source code. This provides benefits in terms of intellectual property protection and quality assurance but sacrifices flexibility and transparency.