
If you are new to Search Engine Marketing and Optimization you might just want to go and get yourself a cup of coffee and take a deep breath. Learning about how to deal with your keywords is necessary!
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Over 80% of all online transactions begin with a keyword search. To compete, you need to target all the relevant keywords." Keyword Discovery
Many of us use keyword research tools in order strengthen our pay per click (PPC) campaigns and improve the website's on-site SEO power. Finding the tool that works for you can effectiviely
make your number of visitors grow exponentially.

I have used
Keyword Discovery simple because I think that this tool is more European oriented, as it supports many different languages, and it is not so Google oriented, which is important in many countries in Europe with a more powerful YAHOO! and MSN presence. But I have not really done any structured benchmarking between the two most used keyword tools - Keyword Discovery and
Wordtracker.
John Alexander from
Search Engine Workshop just wrote a great post in which he compares the two keyword research tools mentioned above -
Wordtracker and Keyword Discovery - How do they compare?
A third very widely used tool that in addition is free of charge is
Keyword Suggestion Tool. "
This is a handy little tool which will show you the results of your query from both Wordtracker and Overture for determining which phrases are searched most often. Enter a search phrase below to see how often it's searched for, as well as get suggestions for alternate (but similar) keywords. Then, once you know the keywords you want to target, you can use the free keyword position tracking tool to monitor your placement progress." Keyword Suggestion Tool.
Final Point - My experience tells me that you must combine the more theoretical approach, which according to me is the usage of a keyword research tool, with the real-life data that you get access to via for example
YAHOO! Search Marketing (YSM) and
Google Adwords. A PPC campaign not only gives you exact data on what your potential customers search for, but also how your webpage convert on every single keyword that you place a bid on.