Since you can include up 10 unique Sitelinks in each AdWords campaign, but only up to four will show in an AdWords ad at any one time, one might wonder how Google determines the combination of links to display.

Our trusted AdWords representative recently shed some light. Until recently, Google pretty much just looked at the order in which you entered your sitelinks in to the AdWords UI. If you entered 10, the first four or sometimes first two entered on that list were generally shown.

Now, Google says there are in fact three main factors (that they’ll divulge…) that go in to determining which of your possible links will appear in the Sitelinks Ad Extension:

1) The order in which you entered the links in the ad extension (still a factor)

2) How well the links perform (CTR)

3) The length of the link text (Google may favor shorter text over Sitelinks Extensions that take full advantage of the 35 available characters)

We look forward to seeing if Google’s optimization of the Sitelinks helps overall performance – now if only they would tell US the CTRs of individual Sitelinks…