How does language targeting work?
When determining where to show your ads, the AdWords system looks at a user's Google interface language setting to see if it matches one of the languages that your campaign targets. For example, only users whose Google interface language is Spanish will see ads in a campaign targeted to Spanish.
Each Google domain's language setting defaults to the language most commonly associated with that Google domain. For example, Google.com defaults to English, Google.fr defaults to French, etc. Users can change their Google interface language via the 'Preferences' link next to the Search Bar on the Google homepage. A Spanish-speaker living in the United States, for instance, may want to perform searches on Google.com but change the interface language setting to Spanish.
You may consider targeting multiple languages to expand your advertising reach on Google. For example, an advertiser may have a website written in English and an AdWords campaign with English ads and keywords. However, he may choose to target that campaign to both English and Spanish. This way, his ads will show to bilingual users who search on his English keywords - indicating that they speak English and would be interested in his website - but whose Google interface language is set to Spanish.
Targeting multiple languages can also increase your ads' exposure across the Google Network. A website in the Google Network can target a certain language, meaning that only ads targeting the same language can appear on that site. For example, a content site in the Google Network may target the Spanish language, which means that your ad would only show on that site if your campaign's language targeting selection included Spanish.
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