Yahoo has improved its online calendar by adding easier to use functions.

A beta version of the calendar has been made available in the UK, US, Brazil, India and Taiwan. The search engine said global rollout will take place over the coming months.

Although Yahoo Calendar and Yahoo Mail are tightly integrated, only about 8.1 million use the calendar out of 278 million mail users, said John Kremer, Yahoo Mail vice president.

The situation is similar among other major providers of webmail and online calendar services, said Matt Cain, a Gartner analyst. Only about three to four percent of consumers also use their preferred webmail service's companion online calendar, he said.

There are various reasons for this, including continued use of paper-based calendars at home and of desktop calendar software like Outlook in the workplace, Cain said.

However, Gartner sees favourable conditions for significantly boosting the use of online calendars among consumers, from around 4 percent in 2008 to 25 percent in 2012, Cain said.

The factors that will drive up usage include increasing industry adoption of open standards that make online calendar services interoperable, he said. This is coupled with an increasing realisation among consumers of the benefits of subscribing to public calendars and sharing their online calendars with friends and family. In addition, younger users are all growing up using online calendars, he said.

"There's no question that online calendars will emerge as a very important part of portal collaboration software offerings for Yahoo, Microsoft, Google and AOL," Cain said.

"For anyone with a big email population, there's no doubt that the next big battleground will be at the calendar level," Cain said, adding that online calendars will become prime real estate for advertising.

Yahoo is hoping that the new Yahoo Calendar will prompt more Yahoo Mail subscribers to use it. Yahoo Calendar hasn't gotten a facelift of this magnitude in about 10 years, Kremer said.

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