The US Hispanic online population is growing.

In 2008, eMarketer estimates there are 23 million Hispanics online, and by 2012 there will be nearly 30 million.

"The paradox is that the larger this market grows," says Lisa E. Phillips, senior analyst at eMarketer and author of the new report, US Hispanics Online: Demographics, "the more fragmented it becomes."

Unfortunately, from a marketer's point of view, US Hispanics do not constitute a homogeneous market.

"Language and degrees of acculturation and assimilation vary by circumstances of age, nationality, education and income," says Ms. Phillips.

People with heritages and traditions throughout Latin America often do not share the same culture—or even the same language.

"Due to the fragmentation within the demographic, online marketers may have to create multiple executions and strategies," says Ms. Phillips.