In any given month, AdWords experiments with numerous subtle variations of the Google search results page, testing everything from font sizes and colors to layouts and spacing, as well as dozens of other variables. Recently, they found that by standardizing the look of the URLs on the page, it had a slight improvement on ad click-through rates.
As a result, they're changing the appearance of the display URLs of all ads that appear on Google and search partner sites. This is a global launch that affects all Google domains. Following the change, the domain portion of the display URL will always be shown in lowercase letters.
The following illustration shows an example of how the ads will be displayed post-change.
This change affects the domain portion of the display URL, including any subdomains. It does not affect any subdirectories or folders that may be included in the display URL. In other words, it affects only the text that comes before the first slash in a URL. Thus, Subdomain.Example.com/Subdirectory would be shown as subdomain.example.com/Subdirectory.
This change also affects all ads that appear for searches that are performed from desktop and laptop computers or mobile devices.
What's Not Changing
At this time, the change does not affect any ads that appear on the Google Display Network, including text ads. This may change in the future.
However, you can continue to use uppercase letters in the headline, description lines, and the portion of the display URL that comes after the first slash.
There's no need for you to make any edits to your ad text. All uppercase letters in your display URL domain will automatically be changed to lowercase when your ad is served.