Google Tag Manager. This allows you to add one small bit of code on your site, which will then load all your other scripts from within the Google Tag Manager interface. This gives you one place (within the GTM interface, inside your Google account) to configure and maintain various scripts. However this adds a layer of complexity, so we only recommend this at the expert level. Most publishers are better off with the simplicty and control of adding the scripts directly on the site (via plugins, or perhaps via the “Header Scripts” section of your theme).