The middle class: it's the world's biggest consumer group and its growing spending power should push global consumer spending up by nearly a third by 2020, according to market research firm Euromonitor.
So, what does it mean to be a middle class consumer?
A study released this week by Euromonitor defined "middle class" consumers as those with a household income in the range of 50 percent below a country's average annual gross household income and 100 percent above a country's average.
While consumer spending in developed markets grew by 2.6 percent annually in the five years to 2012 and should remain low through 2018, emerging markets consumer spending saw double-digit growth of 10.4 percent annually in the same period, Euromonitor said in its survey of 6,600 middle-class consumers in 16 developed and emerging markets.
"The past few decades have seen explosive growth in the middle class in emerging markets, as shoppers with new levels of disposable income are ready to spend and are optimistic about their future," the study said.
(Read more: Why rich consumers will dominate spending in 2013)
About 26 percent of respondents in emerging markets said they intend to increase their overall spending in the next 12 months, while only about half that percentage plan to do the same in developed markets.
Most developed countries have been hurt by weak economic growth in recent years, prompting a change in shopping habits among the middle class, Euromonitor said.
"Regionally, the middle class in the U.S. and Asia-Pacific are prioritizing savings most strongly at 50 percent plus. At the same time, Asia-Pacific respondents are twice as likely as the middle class in other regions to plan to increase their overall spending - 30 percent versus less than 15 percent," Euromonitor said.