An ad group should contain closely related keywords that all speak to a similar theme. Keeping all keywords within a single, tightly themed ad group will allow you to create more targeted ads that will generate a better response, bring more qualified visitors, and improve returns.
To help you get ready, following are some examples of ad groups that follow best practices as well as ad groups that do not.
The following three ad groups each have small, closely themed keyword lists, which will allow us to write specific ad text for each group of keywords:
If an ...