If you are intending to do any kind of pay per click advertising on the internet, you will probably mainly deal with the “Big 3” search engines – Google, Yahoo and Microsoft (MSN). All 3 have fairly similar business models and all work in roughly the same manner. There are however some differences the user should be aware of. One example is how keyword match types have certain differences from Search Network to Search Network.

As a search engine advertiser, it's vitally important for you to know exactly when your ad is going to be displayed. The match type determines whether your ad will be displayed to the user on the basis of how the search query matches your keyword.

As an example, lets say you are promoting a website dealing with digital photography, and one of your key words is "Canon digital camera"

EXACT MATCH

Google:
Exact match in Google will only match the EXACT text and nothing else. Any words before, after, in between or the phrase with words re-arranged will not count. It will only match if "Canon digital camera" is typed in as a search query. "Canon digital cameras" or "Buy Canon digital camera" will not trigger an exact match.

MSN:
Almost identical to Google, but they ignore words like a, an, the etc. Which means that "a Canon digital camera" is considered the same as "Canon digital camera", and is therefore an exact match

Yahoo:
Yahoo have what they term as Standard Match. It not only matches the exact phrase but also includes singular/plural, common misspellings and alternative spellings. The following would all trigger Standard match in Yahoo:
"Canon digital camera"
"Canon digital cameras"
"Cannon digital camera"

PHRASE MATCH

Google:
The ad will be triggered in phrase match any time there is a search query that includes your keywords using the same word order. This means that the phrase "Canon digital camera" must appear somewhere in the user's query. The search can include words before or after your keyword, but not between them. For example

"buy Canon digital camera"
"Canon digital camera on sale"

will both trigger the keyword as a phrase match.

MSN:
The same as Google
Yahoo:
No phrase option is offered with Yahoo search marketing.

BROAD MATCH
Google:
The ad will be displayed any time somebody types in a search query that includes the keywords, regardless of the actual word order. This means there could be additional words in front of, behind, or even in between your original keyword phrase.
There is also some light synonym matching. For example, the following might all trigger the keyphrase "Canon digital camera" on Broad match:

"Used Canon Camera"
"Compare digital camera Nikon and Canon"
"Canon Powershot SD750"

MSN:
Very similar to Google will but will only trigger a search query that includes all of the words. There is also some light synonym matching. Generally not as broad as Google.
Yahoo:
In yahoo it is known as Advanced match and will be triggered by any query that contains all of the words, plus singular/plural, misspellings and synonyms.

It is important to note that in all the search marketing systems, Broad and Advanced are the DEFAULT type of search matches. So be careful as they may not be specific enough to target the market you are trying to reach.

NEGATIVE MATCH

Google:
These are words that block unwanted searches that you believe may not be relevant to what you are offering. For example, if your ad deals with only new cameras you might want to exclude buyers who are looking for used cameras from clicking. So if you include "second hand" as a negative, if a person types in "second hand Canon camera" your ad would not show up.

MSN:
The same as Google

Yahoo:
Known as Excluded Match, is very similar to Google and MSN but singulars and plurals are considered equivalent. For example, if you wanted to exclude people searching for camera lenses, you could put "lens" as an excluded word and the query "Canon digital camera lenses" would not trigger your ad.

Match types play an important role in determining which ads will be displayed for the specific selected keywords. When setting up an ad campaign, try to envision how each match type will affect your keywords. You also need to anticipate keyword variations that may result in unwanted visitors clicking on your ad so that you can filter out non-profitable traffic.