Believe it or not, on average an US ecommerce website has between 15-20 marketing tags. Implementing and maintaining these many marketing tags on your website is often a cumbersome job. Google Tag Manager (GTM) is a great tool for marketer as well as developers. Like any other Tag management solution (TMS), GTM not only decouples deployment of these marketing tags but also introduces an efficient way of sharing data to these tags via data layer.