A SQL query is an automation studio activity that allows querying data from data extensions or data views using SQL statements. A data view is a system-generated table that stores information about subscriber actions, such as clicks, opens, bounces, etc. The _Click data view contains information about each click event for each subscriber in the last six months. By creating and executing a SQL query against the _Click data view, the customer can identify all subscribers who clicked on a link within any email sent within the last six months. Reference: https://help.salesforce.com/articleView?id=sf.mc_as_sql_query_activity.htm&type=5 https://help.salesforce.com/articleView?id=sf.mc_as_data_view_click.htm&type=5