Key Word In Context (KWIC) is the most common format for concordance lines.
[1] The system was based on a concept called keyword in titles, which was first proposed for Manchester libraries in 1864 by Andrea Crestadoro.
[3] It was a useful indexing method for technical manuals before computerized full text search became common.
For example, a search query including all of the words in an example definition ("KWIC is an acronym for Key Word In Context, the most common format for concordance lines") and the Wikipedia slogan in English ("the free encyclopedia"), searched against a Wikipedia page, might yield a KWIC index as follows.
A KWIC index usually uses a wide layout to allow the display of maximum 'in context' information (not shown in the following example).