Описание тега event-tracking
Google Analytics Event Tracking is used to collect data about interactions with your content.
Events are user interactions with content that can be tracked independently from a web page or a screen load. Downloads, mobile ad clicks, gadgets, Flash elements, AJAX embedded elements, and video plays are all examples of actions you might want to track as Events.
Although Event tracking requires a little extra work to set up, we strongly recommend you use it. Events are a flexible way to collect data about interactions specific to your site or app that might not otherwise be tracked.
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