Google Tag Manager is a free tool offered by Google that allows website and app owners to manage and deploy marketing and analytics tags on their websites or apps. A tag is a piece of code that is used to collect and transmit data, such as user behavior or interactions, to a third-party service, such as an analytics or advertising platform. Google Tag Manager allows users to manage their tags in a single location, and to update or change their tags without the need to modify their website or app code. This can save time and resources, and can make it easier for users to implement and manage their tags. Analytics tags are different from ad tags, which send requests to an ad server to retrieve an appropriate ad.