The act of beginning a line or series of lines at a little distance within the flush line of the column or page, as in the common way of beginning the first line of a paragraph.
Whitespace inserted at the beginning of a line. Different textual areas in input files use different, user-configurable rules to determine the type and amount of whitespace.
Indentation is the blank space at the beginning of a line. Lisp, like many other programming languages, has conventions for the indentation of code to make it more readable. The editor is designed to facilitate such indentation.