Despite the fact that the Internet has been widely available for over a decade in most developed countries, recent data from Nielsen//NetRatings show that there continue to be new converts to the technology. Active at-home Internet users in the US grew 3.1% between October 2005 and October 2006, reaching 146.5 million. Countries such as France and Spain recorded growth of over 20% in the same period, while there was a strange drop in the number of Internet users in Italy.


Early in the new year, eMarketer will re-examine its global Internet user forecasts, but it is useful now to revisit the definition of an "Internet user." Nielsen//NetRatings, which claims to measure 70% of the world’s Internet population, always publishes two figures when assessing the size of the Internet audience in a country. One figure represents the total digital media audience and the other represents the active digital media audience. The former (larger) measure could be said to represent the number of people with Internet access (usually at home and work), while the latter (smaller) measure represents those who have Internet access and use it regularly.

eMarketer defines an Internet user as an individual (ages 3 and older) who uses the Internet at least once per month. This is closer to Nielsen//NetRating’s definition of an "active" Internet user. For online advertisers, marketers, retailers and service providers, an active Internet user measurement is a more useful snapshot of the current "marketable" Internet audience, while the broader measure provides an estimate of the potential online market.

A comparison of the different estimates of Internet users in the United States in 2005 illustrates clearly how different definitions of an Internet user can have a significant impact on the measurement.

The same can be seen in estimates of Internet users in the leading Internet markets of Europe. The difference between the number of active Internet users at home and the total number of people with Internet access at home or work in the five largest European markets is over 50 million, according to estimates from Nielsen//NetRatings. This compares with eMarketer’s estimates, which fall somewhere between the two extremes and is a measure of active Internet users ages 3 and older from all locations.

Measuring an Internet audience is no mean feat and the different estimates from different firms is a testament to that. It is one of the main reasons why eMarketer tries to provide as many different estimates as possible so a clearer idea of the "truth" will be revealed.

More here.