Defining the keyword match type in a Google Adwords campaign can make the difference between the success and failure of a campaign. The 5 match types that are available are broad match, broad match modifier, phrase match, exact match, and negative match. Each match type has its advantages and disadvantages which can greatly change the outcome and effectiveness of a campaign.
The broad match keywords are not denoted with any special annotation. Broad match gives the most control to Google in terms of its ability to match a keyword with a variation, misspelling, or synonym. For this reason a broad match keyword tends to receive a high amount of clicks, but a low conversion rate. It will also drive traffic for a campaign, but because of the wide net that it casts will not always draw the right type of traffic. However, it also has the potential to target keywords that were not thought of in initial planning stages that can be very successful.
The next step down the spectrum is broad match modifier, which is denoted by have a +plus +sign in front of the keyword with no space between. Modified broad matches will contain close variations of the keyword, but will not contain synonyms. The modified broad keyword offers some refinement that will restrict your ad to coming up to more accurate terms. This generally results in a reduction in traffic, but a boost of effectiveness from that traffic.
Next we have phrase match type keywords which are more specific still. A phrase match keyword is displayed within “quotes” in the AdWords interface. With a phrase match the keyword that is provided will appear in all search terms in the order that it is written, with only slight variations such as plural/singular. This gives your further control of what search terms will trigger ads, but can also see very limited traffic. Many times phrase match keywords can result in low search volume messages, but they can also be very effective when dealing with highly competitive topics.
The last and most specific match type is exact match, which is marked by having [brackets] around the keyword. With an exact match keyword, ads will only show when the search term used is a direct match, letter for letter, as the keyword. This can be very useful when dealing with highly competitive keywords and generally results in the most targeted traffic that you can achieve. However, this match type can be difficult to find terms with enough search volume and you also may end up missing out on search terms that you were unaware of.
In addition to those match types, there is also negative keyword matches, which are created by putting a -negative sign in front of the keyword. Negative keywords will prevent an ad from coming up for that keyword. For more information on the importance of negative keywords check out The Importance of Negative Keywords In Google Adwords.