If you use Google Adwords for your online ad campaigns, it is highly recommended that you enable auto-tagging in order for Google Analytics to display details about your AdWords keywords and costs. This will ensure that you get the most detailed AdWords data in your Analytics account.
Auto-tagging automatically imports AdWords data into Analytics. Combining AdWords data with the rich post-click information provided by Analytics allows you to see what happened on your site after people clicked on your ads.
When you enable auto-tagging, a parameter called gclid is added to your landing page URL when a user clicks over to your site from an ad. For example, if your site is www.mysite.com, when a user clicks on your ad it appears in the address bar as:
Using auto-tagging exclusively provides several benefits over manual tagging. Manual tagging can be time consuming and will only allow you to see a subset of AdWords data. You can read more about the benefits of auto-tagging.
How To Enable Auto-Tagging in Adwords
To enable/disable auto-tagging:
==> Sign in to your AdWords account.
==> Click the gear icon, and select Account settings.
==> Make sure you're on the Preferences tab, and click Edit in the Tracking section.
==> Select (enable) or clear (disable) the Auto-tagging checkbox.
==> Click Save changes.
>> Autotagging automatically tags the Source/Medium of your AdWords ads as "google/cpc" in Analytics
>> Manual tags should not be used on AdWords ads at the same time as autotagging as this may result in conflicting data in your Google Analytics reports.