Where should the data layer object be placed in the website code?

The data layer object must be initialized before the Google Tag Manager container snippet. This ensures that when the GTM container loads, the data layer is already present and populated with any initial values. GTM reads from the data layer as soon as it executes, so if the data layer is defined afterward, GTM will miss those initial values, leading to tracking inaccuracies. Placing it after the container snippet means GTM won't see the initial data. Placing it inside the container snippet is syntactically incorrect and will cause errors. Placing it at the bottom of the HTML would also mean it loads too late for GTM to capture initial page load data.