What is Google Tag Manager?

Source: Google Tag Manager

Google tag manager (GTM) is a free tag management platform created by Google that enables marketers to quickly deploy, update and track marketing data by easily adding code snippets, known as tags to their website or app.

Google tag manager is communicating with the website or app, where the code snippets were added, providing marketers a powerful web-based user interface to manage, set up and add tags, track conversions, website analytics, retargeting, and more without the intervention of a webmasters.

Google tag manager was not built to replace Google analytics as they are actually working in conjunction to give marketers an easy-to-manage, flexible system of tracking various analytics.