Google Webmaster Tools added support for a new website verification method, called Google Tag Manager as announced in WMT Blog.

This option is visible in “Alternate Methods” at the bottom when you try to add a new site and on the verification page, shown as follows:

Google Tag Manager  Use your Google Tag Manager account.

The Google Tag Manager container ID is used only to verify site ownership. No Google Tag Manager data will be accessed.

If you are new to Google Tag Manager then I will let you know that you can use Google Tag Manager without much knowledge of coding etc. It lets you add and update your website tags very easily and for free and whenever you need.