diff --git a/error.c b/error.c
index 878ec81d13..ec161e5662 100644
--- a/error.c
+++ b/error.c
@@ -3012,14 +3012,28 @@ syserr_eqq(VALUE self, VALUE exc)
 /*
  *  Document-class: NotImplementedError
  *
- *  Raised when a feature is not implemented on the current platform. For
- *  example, methods depending on the +fsync+ or +fork+ system calls may
- *  raise this exception if the underlying operating system or Ruby
- *  runtime does not support them.
+ *  Raised when a method is called for a feature that is not implemented.
  *
- *  Note that if +fork+ raises a +NotImplementedError+, then
+ *  This may be raised when the current platform does not support certain features.
+ *  For example, methods depending on +fsync+ or +fork+ system calls may raise
+ *  this exception when the underlying operating system or Ruby runtime
+ *  does not support them. Note that if +fork+ raises a +NotImplementedError+, then
  *  <code>respond_to?(:fork)</code> returns +false+.
- */
+ *
+ *  This may also be raised by abstract methods which require implementation by
+ *  an extending class in the calling application or library. For instance:
+ *
+ *    def calculate
+ *      raise NotImplementedError, "#{__method__} needs to be implemented by the extending class"
+ *    end
+ *
+ *  <em>raises the exception:</em>
+ *
+ *    NotImplementedError: calculate needs to be implemented by the extending class
+ *
+ *  Keep in mind: NotImplementedError is not a descendant of StandardError and will
+ *  not be rescued by a rescue clause without an explicit Exception class.
+*/
 
 /*
  *  Document-class: NameError