Programming language

• A programming language is a systematic method to describe computations. Programming languages are most commonly used to describe an intended computation in a form that will allow it to be performed by an electronic computer. Programming languages exist because other forms of human expression such as natural languages are not well-suited to describing computation in sufficient detail to be performed reliably by an electronic computer.
  
  
  Computations expressed in programming languages are generally called programs, and the act of constructing these programs is called programming or, colloquially, coding. The human-readable description of a program written in a programming language is called code. Code that is written in a high-level programming language is usually called source code.
  
  The task of transforming the source code into a sequence of operations performed by a computer can be compared to translation between human languages, and indeed the same word, translation, is sometimes used. There are two basic families of translation, designated according to whether the translation takes place before or during the process of performing the calculation.
  
  An interpreter is a program that takes code in the source language and causes the computer to perform a computation according to the semantics of the language.
  
  A compiler is a program that takes code in the source language and translates it into code in another, lower-level language, so that an interpreter for the lower level language can be used to implement an interpreter for the high level language. The lowest level language is a sequence of instructions which can be directly interpreted by the computing machinery itself; this is known as machine language, or more usually machine code.
  
  Computer programs can thus be executed using some combination of compilation and interpretation.
  
  As descriptions of computations expressed in a programming language are highly detailed and precise, they are frequently rather difficult for other humans to follow, and may even give the original programmer difficulty after some time has elapsed. So it is considered good programming practice to add comments in some natural language to the source code. These comments are ignored by the computer, but are often critical to allowing another human to easily understand the code.