What is Keyword Difficulty?
 

What is Keyword Difficulty?

Understanding keyword difficulty will help you to choose which queries to compete for, both now and in the future. It comes down to three things. Competition. The number of pages indexed by a search engine for a query. Authority.

I'm not quite sure that Keyword difficulty identifies how difficult it would be to rank well for a particular keyword. and the value is higher for more popular words because it will be more difficult to compete with 1,000s of other sites for a popular word than with 10s of others for the less popular ones.

Keyword Difficulty is calculated by the SEOMoz research tool that considers various things including: competition , how many people are bidding on the term in paid search and what number of individuals are really looking for the term online