An Internet subscription system for alerting subscribers to changes in data maintained at Internet sites has an input interface for a subscriber to specify a data condition to be monitored and a condition for notification and a gatherer for gathering data changes from one or more Internet sites. A guard compares data changes with the condition for notification, and a notification alert system notifies the subscriber of a change that meets the condition for notification. The system is particularly suited to notification requirements regarding metadata changes over multiple sources. Users can configure the system to many different frequencies and many different data and notification conditions. Alerts may be made to many different devices in different ways as well, and may or may not include specific data.