The reason why it’s important to distinguish between these types of implementation is because a web page loads from top to bottom. If you use a synchronous ad tag, the tag loads in sequence with the page content. The page won’t load until the entire piece of code loads, which could create slower pages and slight delays. On the other hand, asynchronous ad tags load independently of the other elements on the web page. The page will load more quickly, but the user could begin to navigate before your tags have finished loading.
Synchronous tags can be helpful in certain situations, like running an A/B test. Asynchronous tags are generally better for tracking and collecting data.
Tag managers are hosted on a content delivery network (CDN). In this type of interface, marketers define what data, tags, and customer behaviors are important. Based on that information, the tag manager creates a tracking code and inserts the new tag onto your web page.