7 In most practical contexts, a programming language involves a computer; consequently, programming languages are often outlined and studied this fashion. However, there are some programming languages which are more graphical in nature, utilizing visual relationships between symbols to specify a program.
Robert W. Sebesta : Ideas of Programming Languages, ninth ed., Addison Wesley 2009. There are lots of ways to rank programming languages, just like the variety of websites constructed with them, Google search results, GitHub projects or StackOverflow questions.
Programming languages differ from most different forms of human expression in that they require a better degree of precision and completeness. A programming language supplies a structured mechanism for defining pieces of knowledge, and the operations or transformations which may be carried out mechanically on that information.