Azure Log Analytics is the service within Azure Monitor that is designed specifically to perform log data aggregation and complex querying. It lets you analyze data across multiple virtual machines, enabling the detection of trends and patterns. In contrast, Application Insights provides application performance insights but isn't used for extensive log data analysis across VMs. Azure Monitor alerts enable you to set up alert rules based on metrics or logs, but do not involve data aggregation or complex querying. Azure Service Health notifies you about Azure service incidents and maintenance, but is not used for log data analysis.