Thanks Linda for yr clear and concise reply that help to remove away some of my doubts.
Let say we launch a campaign, do we need to use all the keywords under the same Ad Group, for e.g say someone does a search on "dogs treat", does the keyword under "dog brush" also appear in the search?
BTW, you were saying that those under Sponsord Links are "free traffics". Does it means that these ads are from those who submitted their blogs or articles? How about the
SEO? Are they related to each other in some ways?