Proprietary software, also known as closed-source software, is software whose source code and design information are not publicly available. This means that the source code of the software is typically kept secret, and only the executable program or application is made available. Access to the source code and the ability to modify or distribute it is usually heavily restricted by licensing agreements.

Here are some key features and aspects of proprietary software:

1. Licensing: The use of proprietary software typically requires a license or permission from the owner or manufacturer. Usage rights are usually spelled out in precise terms within the license agreement.

2. Closed Source Code: The source code of the software is not publicly accessible. This means that developers and users do not have access to the code that determines how the software functions.

3. Limited Customization: Due to the closed source code, users are unable to freely customize or modify the software. Changes to the code are typically only possible through the manufacturer or provider.

4. Restricted Distribution: The distribution of proprietary software is often governed by licensing restrictions. Users are typically not allowed to copy or distribute the software without permission.

5. Business Model: Manufacturers of proprietary software often follow a business model where they sell licenses or subscriptions for the use of their products. This can generate revenue to support software development and maintenance.

6. Support and Updates: Manufacturers of proprietary software typically offer support and regular updates for their products to fix bugs and enhance performance.

7. Examples: Examples of proprietary software include Microsoft Windows, Adobe Photoshop, and many commercial video games.

It's important to note that the term "proprietary software" does not necessarily carry a negative connotation. Many successful software products and companies are based on proprietary software. Companies that develop proprietary software often have control over the development, quality assurance, and support of their products, which can lead to stable and well-supported software.

In contrast, open-source software makes its source code publicly accessible, allowing developers the freedom to view, modify, and distribute it as long as they adhere to the licensing terms. Open-source software promotes collaboration and free knowledge exchange, while proprietary software emphasizes control and protection of intellectual property.