Google has long supported keyword matching options in Adwords pay per click campaigns. For those of you who are unfamiliar with keyword matching, the standard options include:
Broad Match
Ads will be displayed when any combination of the words in your broad match phrase (or synonyms or related phrases) appear in a search query, regardless of the order.
Context: keyword phrase
Example: search engine optimization
Ads will show up for search queries including: search engine optimization, search engine optimization company, optimization for a search engine, seo company
Phrase Match
Ads will be displayed when any combination of the words in your broad match phrase appear in a search query, in the exact order you specify.
Context: "keyword phrase"
Example: "search engine optimization"
Ads will show up for search queries including: search engine optimization, search engine optimization company, google search engine optimization
Exact Match
Ads will be displayed only when the exact phrase you specify is searched. The words must be in the exact order you specify and no other words can be included in the query.
Context: [keyword phrase]
Example: [search engine optimization]
Ads will only show up for the search query: search engine optimization
Google's new keyword matching option, called broad modifier, gives slightly more control over what search queries your ads show up for than with traditional broad match. The modifier will limit the synonyms and related searches that your ads will show for when using broad match. To use the modifier, insert a + symbol before one or more of the words in a broad match phrase. For any word with a + symbol preceding it, a search query must include that word or a very similar variation in order for an ad to be displayed. Below are some examples:
If your broad match phrase is red diamonds then your ad may show up for phrases including:
red jewelry, colored jewelry, cheap fake red diamonds
If your broad match phrase is +red diamonds then your ad may show up for phrases including:
red diamond, red jewelry, red necklace
If your broad match phrase is +red +diamonds then your ad may show up for phrases including:
red diamond, cheap diamonds in red, red elegant diamonds
Basically, using broad match modifiers will give you more reach than using phrase match, but more control than using traditional broad match.
