English

An indentation can mean two things:

• To make notches in something or form deep recesses in a coastline for instance.
• To place text farther to the right to separate it from surrounding text.

The first meaning is also applied in hardness measurement as in indentation hardness. In materials science, hardness is the characteristic of a solid material expressing its resistance to permanent deformation. ... In materials science, hardness is the characteristic of a solid material expressing its resistance to permanent deformation. ...

For an example of the second meaning, this is an indentation of one space:

Indented block

and this is an indentation of two spaces:

Indented block 2

In the written form of many American and European languages, an indentation is often used at the beginning of a line to signal the start of a new paragraph.

Outdentation is a neologism used in computer circles to describe placing text back to the left again.

Indentation in programming

In computer programming languages, indentation is used to format program source code in order to improve its readability. Indentation is generally only of use to programmers; compilers and interpreters rarely care how much whitespace is present in between programming statements. However, certain programming languages rely on the use of indentation in order to demarcate programming structure, often using a variation of the Off-side rule. The Haskell, Occam, and Python programming languages rely on indentation in this way. A programming language is an artificial language that can be used to control the behavior of a machine, particularly a computer. ... Source code (commonly just source or code) is any series of statements written in some human-readable computer programming language. ... A diagram of the operation of a typical multi-language, multi-target compiler. ... An interpreter is a computer program that executes other programs. ... For information on the programming language Whitespace, see Whitespace programming language. ... A computer programming language is said to adhere to the off-side rule if in it the scope of declarations (a block) is expressed by their indentation, i. ... Haskell is a standardized pure functional programming language with non-strict semantics, named after the logician Haskell Curry. ... Occam is a parallel programming language that builds on Communicating Sequential Processes (CSP) and shares many of their features. ... Python is an interpreted programming language created by Guido van Rossum in 1990. ...

Debates over where to indent, whether to use spaces or tabs, and how many spaces to use are often hotly debated among programmers, leading some to classify indentation as a religious war. Different indentation styles are commonly used. Recently, a third method of indentation was proposed, called elastic tabstops. Tab may refer to: The tab key, used to indent text to a preset horizontal position. ... For other uses of the term, see Holy War. ... In computer programming, an indent style is a convention governing the indentation of blocks of code to convey the programs structure. ... In text editor applications in computing, an elastic tab stop is an alternative way to handle tab stops, with a primary focus on editing source code in computer programming. ...