Overview

Proprietary software (often called closed-source software) is distributed under terms that prevent users from freely inspecting, modifying or redistributing the program's source code. The publisher—usually a company or organization—retains exclusive control over the code, deciding who may view, copy, or change it. Some proprietary programs are sold for a fee; others are provided at no charge to end users but remain closed in terms of source access and modification rights.

Key characteristics

Typical features of proprietary software licenses and distribution include:

  • Source code withheld from the public; only compiled binaries are distributed.
  • License agreements (EULAs) that limit copying, modification, redistribution and reverse engineering.
  • Restrictions on installation scope, device use, or number of users.
  • Copyright, trade secret protection and sometimes technical measures such as digital rights management (DRM).

Origins and development

The proprietary model grew alongside commercial computing and became dominant in many software markets as companies sought to protect intellectual property and monetize development. In response, alternative movements advocating access to source code and user freedoms — commonly grouped under "free" or "open-source" software — emerged to promote transparency, collaboration and reuse. The two approaches now coexist and sometimes intersect: vendors may combine closed and open components, or use dual licensing strategies.

Uses, advantages and disadvantages

Proprietary software is common in desktop applications, enterprise systems, specialized industrial control systems and many consumer devices. Vendors argue that restricting source access protects investments, supports commercial support and quality control, and helps ensure a consistent user experience. Critics counter that lack of transparency can impede security auditing, encourage vendor lock-in, and limit interoperability. Whether proprietary software is preferable often depends on needs for support, liability, features, and total cost of ownership.

Legally, proprietary status is enforced by copyright and license terms; contracts may prohibit modification, redistribution or claims of authorship. In some cases a developer may share source under narrow terms (for auditing or partnership) without granting broader rights. Users evaluating software should examine license terms, update and support policies, and whether open standards or exportable data formats are available to reduce dependency on a single vendor. For background on the contrasting philosophy, see free software, and for related concerns about attribution and copying see plagiarism.