Google Alerts is a content change detection and notification service, offered by the search engine company Google, that automatically notifies users when new content from news, web, blogs, video and/or discussion groups matches a set of search terms selected by the user and stored by the Google Alerts service.

Rightly said.......and we can also subscribed the Google alerts via our email.

A Google alert is a notification delivered to one's email or information feed that informs users of new content that has appeared on the web. There are a number of reasons why people use this sort of content-monitoring service.