I'm writing a paper about software law and need to describe software libraries accurately from a computer science perspective. Legally, the distinction seems fairly clear, but technically I'm unsure how the terms relate. Is a library a type of software, a collection of programs, or something else? Is "software" simply a collection of programs, or is it a broader category? The terminology seems inconsistent, so I'd appreciate a clear explanation of the usual meanings and any important caveats.
5 Answers
The terminology is not perfectly formal. In common programming usage, “software” is normally a mass noun—you would say “some software” or “a piece of software,” not “a software.” A library is therefore a piece of software, but it is usually not called a program because it is not intended to run independently. That said, scripts, plugins, modules, and interpreted code can blur the boundary.
For a legal paper, be careful not to assume that everyday computer science terminology controls the legal meaning. “Software,” “computer program,” and “library” may be defined differently by legislation, contracts, or court decisions. It would be reasonable to describe a library as software consisting of reusable code that is generally incorporated into or used by a program, then cite the specific legal definitions that apply to your subject.
A library is usually part of a program rather than a complete program itself. For example, an application might use SQLite for database access or OpenSSL for encryption. The library supplies reusable functionality, while the application provides the overall behavior and entry point. Static libraries may be incorporated into the final executable, while shared libraries can be loaded separately at runtime.
One way to think about it is that a program has an entry point: there is a defined place where execution begins when the operating system or another host starts it. A library is more like a toolkit or recipe collection. It contains code that can be called by a program, but it does not usually begin executing on its own. This is a practical convention rather than a universal technical or legal definition.
Software is the broad category. Programs and libraries are both types of software, along with operating systems, drivers, and other components. A program is generally something that can be started or executed as a standalone application. A library is usually reusable code—functions, classes, types, or other definitions—that another program links to or loads. It normally does not have its own standalone entry point.
That distinction is useful, but it is not absolute. Some libraries can be loaded or initialized in ways that look like execution, and plugins may have entry points while still being treated as libraries or components.