Auto-tagging is used to collect data from which kinds of traffic?
Social media traffic
AdWords Campaign traffic
Search engine traffic other than Google
Website referral traffic
Auto-tagging is the recommended approach and ensures that you get the most detailed AdWords data.
Read more here: https://support.google.com/analytics/answer/1033981
Tag your AdWords final URLs
In order for Analytics to display details about your AdWords keywords and costs, you must do one of the following:
Enable auto-tagging. This is the recommended approach and ensures that you get the most detailed AdWords data.
Manually tag all your keyword final URLs with tracking variables. You should only do this in the special cases outlined below.
We strongly recommend that you use auto-tagging.
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:
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.
Learn more about the benefits of auto-tagging.
Your website doesn’t allow arbitrary URL parameters
A small percentage of websites do not allow arbitrary URL parameters and serve an error page when auto-tagging is turned on. Consult with your webmaster to find out if this is the case, or turn on auto-tagging and do a test by clicking a live version of your ad (for example, do a Google search that displays your ad and click that). If the link to your site works, then you can use auto-tagging. If you get an error, you need to turn auto-tagging off from your AdWords account. Then, ask your webmaster to allow arbitrary URL parameters before turning it back on.
If allowing URL parameters is not a workable solution, you can tag your links manually. However, manual tagging can be time consuming and will only allow you to see a subset of AdWords data.
Use caution when manually tagging your links:
Tag your actual final URLs with parameters. If you try to use a redirect from a final URL to another URL + parameters, your AdWords data won’t be transmitted to Analytics.
Remember to disable auto-tagging. If you unintentionally mix manual and auto-tagging, you’re likely to encounter data discrepancies.
You need to use auto-tagging for non-Analytics purposes
If you need to (1) turn on auto-tagging in your AdWords account for purposes other than Analytics tracking and (2) wish to use manual tagging for Analytics, then you must enable the auto-tagging override setting to avoid data discrepancies:
Sign in to your Analytics account.
Click Admin and navigate to the relevant property.
In the PROPERTY column, click Property Settings.
Under Advanced Settings, select Allow manual tagging (UTM values) to override auto-tagging (GCLID values) .
Note: If you have linked your DoubleClick Search account to your Analytics account, then this setting will also apply to all clicks coming from search campaigns managed in DoubleClick Search.
This setting enables Analytics reports to use UTM values for Campaign, Term, and Content that you’ve specified via manual tagging. If you haven’t specified UTM values for one or more of these parameters, Analytics uses the auto-tagged values for those parameters instead.
You specify utm_campaign = “foo”.
Analytics reports use:
Campaign = “foo”
Auto-tagged values for all other parameters:
source = “google”
medium = “cpc”
term = [auto-tagged value from AdWords]
content = [auto-tagged value from AdWords]
Analytics also continues to join these clicks with AdWords. As a result, you can:
Access richer data in some Analytics reports, such as Final URL, Shopping Campaigns, and Video Campaigns.
Import Analytics goals and transactions into AdWords conversion tracking.
Import Analytics data to AdWords reports.
Note: For clicks to appear in the Analytics AdWords reports, they must have a Source/Medium of google/cpc. This means that if you manually tag either source or medium, Analytics will use the manually provided values, but you will not:
See these clicks in the AdWords reports in Analytics or
Be able to import Analytics goals and transactions into AdWords conversion tracking.