A tag is a piece of code that sends information to a third party, such as Google Analytics.
Tags are often provided by analytics, marketing, and support providers to help you integrate their products into your website or mobile app.
In Google Tag Manager, you can deploy a tag using a built-in template. Many templates are built into Tag Manager directly. If a template is not available for the tag you want to deploy, you can still implement them via Tag Manager using custom tags.
Tags in the digital marketing and analytics context are similar to, but distinct from, the standard HTML tags that developers will use to code web pages. The analytics sense of the word tag is derived from the fact that the tracking codes provided by vendors are often encapsulated by HTML
In other words: When we speak of HTML tags, we're referring to tags such as
<blockquote>, and so on. When we speak of analytics/tracking/marketing tags, we are referring to the block of code that the provider has given us to install their tracking code or functionality onto our website or mobile app.