The Market Opportunity Score (or MOS) of a keyword phrase is a number calculated by Coach's Keyword Tool that essentially tells you how easy it will be for you to outrank the top competitors for that particular keyword phrase. The higher the MOS, the faster and easier it should be for you to pass up the sites that currently rank at the top of Google for that keyword phrase.

Coach's Keyword Tool evaluates several of the top factors that search engine algorithms consider when ranking web pages. By looking at these factors, the tool basically determines how "weak" or "strong" the competition is. If the majority of the top competitors are relatively "weak", the MOS will be high (closer to 100). If the top competitors are relatively "weak", the MOS will be low (closer to 0).