You can set up your AdWords campaign to be responsive to different types of search queries. You can be as strict as requiring exact key phrase matches, as loose as requiring only partial keyword matches or jumbled words in the phrases, or even exclude certain words from the keyword set.

• Broad match. This is the most comprehensive option, and the default setting for keywords. This way, your ads will be displayed in queries for any keyword or phrase in any order. Your ad will also appear in searches that include words you did not specify. The advantage is that you do not have to type in all possible key word or phrase combinations. However, your conversion rates (the relevance and hence clickthroughs) may not be as high, since a high level of relevance is not always assured.
• Expanded match. This is also turned on by default. Google will also display your ads on queries highly relevant kewords (related to the ones you specify) even if you do not specify them yourself, or even if only one or a few of your keywords are searched. The advantage is that your ad appears in more searches, but may not always appear to be relevant.

Next: Alternative / non-default options.