Why is it desirable to escape/strip this character from user provided data? [duplicate]

Why is it desirable to escape/strip this character from user provided
data? [duplicate]

References

Reference NO 1

http://search.cpan.org/~evo/String-Escape-2010.002/Escape.pm

Reference NO 2

http://stackoverflow.com/questions/16575268/which-characters-must-be-removed-escapes-from-php-forms-in-sql-queries

Reference NO 3

http://php.net/manual/en/function.stripslashes.php

Reference NO 4

http://jinja.pocoo.org/docs/templates/

Reference NO 5

http://lukeplant.me.uk/blog/posts/why-escape-on-input-is-a-bad-idea/

Reference NO 6

http://closure-library.googlecode.com/svn/docs/closure_goog_string_string.js.html

Reference NO 7

http://www.freeformatter.com/

Reference NO 8

http://perldoc.perl.org/Term/ANSIColor.html