is the percentage (or portion) of sales of a product, company or brand in a given region or country
is used by companies to determine their competitive strength as compared with other companies in the same sector or industry
is used by companies to review their competitive performance from year to year
is not always readily available - it often has to be pieced together from information found in a variety of sources (e.g., newspaper & magazine articles, industry & company reports, web pages, personal contacts, etc.)