To recap from the Why Is Google Adwords the Keyword to Success? Blog post, when a ‘search query’ is created, this in turn ‘triggers’ a keyword that is included in an advertisers campaign.
Therefore, it is of paramount importance to include keywords in your campaign that are most relevant to the search query.
To ensure this, keyword research has to be carried out. The fundamental reason why you have to carry out keyword research is to detect the most competitive keywords in your marketplace.
But there is more that has to be considered. Synonyms are also crucial, as the search query could contain a terminology that Google does not recognise as being relative to your product.
This also applies to variations of spellings, as people tend to type in misspellings within their search query.
Undertaking this research can assist you immensely.