  Majority of the currently available webpages are dynamic in nature and are
changing frequently. New content gets added to webpages and existing content
gets updated or deleted. Hence, people find it useful to be alert for changes
in webpages which contain information valuable to them. In the current context,
keeping track of these webpages and getting alerts about different changes have
become significantly challenging. Change Detection and Notification (CDN)
systems were introduced to automate this monitoring process and notify users
when changes occur in webpages. This survey classifies and analyzes different
aspects of CDN systems and different techniques used for each aspect.
Furthermore, the survey highlights the current challenges and areas of
improvement present within the field of research.
