Google Tag Manager is a tag management system (TMS) that allows us to easily update marketing tag snippets/codes/tracking pixel on a website. It helps to manage website tags without editing code of a themes.
Manager gives you the ability to add and update your own tags for conversion tracking, site analytics, remarketing, and more. There are nearly endless ways to track activity across your sites and apps, and the intuitive design lets you change tags whenever you want. It helps to deploy Google and third-party tags easily.
Reallly Simple Google Tag Manager WordPress plugin is developed by HasThemes team to add the Google Tag Manager Script to a theme code without touching any code. It makes easier to enable or disable the tracking code.