Hispanic online users represent a lucrative customer base marketers want to reach, according to eMarketer's new report, Hispanic Americans Online: A Fragmented Population.

An estimated 18.8 million Hispanic Americans are Internet users in 2007. That number will grow to nearly 25 million by 2011, with a steady double-digit annual growth rate in the next four years, according to the report.

About half of the people added to the U.S. population between 2005 and 2006 were of Hispanic origin. Based on U.S. Census Bureau's estimate, in 2006 the number of Hispanic Americans was 44.3 million, or 14.8 percent of the U.S. population, expected to grow to 47.8 million or 15.5 percent by 2011.

“A defining characteristic of this segment is the variety of its nationalities, languages, degrees of acculturation, income and education levels.” said Debra Aho Williamson, eMarketer Senior Analyst and author of the new report. “These factors yield a patchwork of Internet usage patterns. The nearly 19 million Hispanic American Internet users do not constitute a homogeneous market.”

Hispanic Americans come from nearly two dozen countries. Nearly two-thirds are of Mexican origin, while many other nationalities are represented.

“The relative youth of the Hispanic population also affects marketing decisions,” said Williamson. According to the Census Bureau, Hispanic males have a median age seven years younger than the total U.S. population, while Hispanic females are a median of 10 years younger.

“The growing Hispanic online market will constitute an attractive audience for marketers and media companies well into the future,”. Williamson said. “But the larger the population, the more diverse it becomes and thus the more challenging to reach.”