The next frontier in advertising is tracking users across their devices.

Advertisers would love to know your whereabouts based on your smartphone and tablet usage. Many companies are helping them achieve that goal.

Right on Target

Firms are employing a number of new methods to better serve more relevant ads to groups of people on mobile devices.

Look-Alike Modeling
Ad-technology firms like Tapad and Exelate analyze mobile and e-commerce data to create segments of people who are likely to buy certain kinds of products based on similar demographics, online usage and purchasing behavior.

Day-Parting
Google can serve mobile ads during specific days and times of the week, so ads can display phone numbers when stores are staffed, for example, or promote certain brands at night when people are more likely to use tablets.

Cross-device Marketing
The next frontier in advertising is identifying multiple devices used by one person. Drawbridge’s algorithms try to anonymously match devices by triangulating ads requested by different devices across similar times and locations.

Credit: Wall Street Journal.

Apple’s market share fell to 18% in the January-March quarter from 23% in the same period a year earlier, whereas Samsung Electronics Co. captured its highest-ever share of 33% from 29%.

People familiar with the iPhone’s production told The Wall Street Journal this month that Apple is working with manufacturing partners in Asia on a less expensive iPhone that could be released as early as the second half of this year.

Swiss engineers have designed a plane capable of flying around the world - without burning an ounce of fuel.

A South Korean manager leaving the Kaesong joint industrial complex in North Korea—with no certainty that any property abandoned won’t be seized by Pyongyang—arriving heavy laden at the inter-Korean transit office in Paju, South Korea.

The Bank of Japan’s promised to inject ¥60 trillion to ¥70 trillion ($610 billion to $710 billion) per year into the financial system. The bigger problem though is how monetary easing filters through to household income and consumption. The average monthly earnings of Japanese workers actually fell 0.7% in February from a year earlier. The participation of women and immigrants in Japan’s labor force remains too low given the country’s aging and shrinking population.

Some great business ideas seem so simple we wonder why no one ever thought of them before. The backstory behind a bunch of household names, and tips to open your mind to inspiration.

80% of consumers change purchasing decisions based on negative online reviews.

NASA has released images of a hurricane over Saturn’s north pole. Scientists estimate the eye of the storm to be about 1,250 miles across with clouds traveling as fast as 330 miles per hour.

Justice Is Blind, but Not Bald

Lawyers in hot, humid Hong Kong are fighting over who should get the privilege of wearing a horsehair headpiece in court.

Judges wearing wigs attend a ceremony to mark the beginning of the new legal year in Hong Kong on Jan. 9, 2012.

In hypermodern Hong Kong, a debate over 17th-century fashion is dividing the city’s legal circles. The city’s lawyers are among the last in the world to wear judicial wigs, those curly, horsehair headpieces that are a legacy of more than 150 years of British colonial rule. The affection is so great that one group of lawyers that doesn’t wear wigs wants the right to don them. The city’s wig-wearers are resisting.

The split over wigs mirrors the divide in Hong Kong’s legal profession. As in the U.K. and some former British colonies, Hong Kong’s lawyers are split between solicitors, who work directly with clients, and barristers, who represent those clients in court. The difference has historically been easy to spot: Barristers, like judges, work in an elaborate uniform of robes topped with hand-woven hairpieces.

For years, solicitors have been expanding their professional reach into areas traditionally considered barristers’ turf. In 2010, solicitors in Hong Kong gained the right to apply for a special status that would allow them to represent their clients in higher courts. But still, barristers are reluctant to embrace more curly-haired colleagues.

Credit: Wall Street Journal.

As unemployment rises to 27.2% of the workforce, the Spanish government said it was easing up on austerity and developing new measures aimed at breathing life into an economy that it acknowledged was even weaker than previously thought. Friday’s budget is another sign that supporters of austerity are losing the political battle in Europe as the social cost becomes too high.

Japan’s stock rally is chugging toward the six-month mark and is still going strong as the country pulls in large global investors, sending trading volumes to a record high.

The aedes mosquito, the carrier of the potentially fatal dengue fever, has been a constant nuisance for Singapore. But the threat looms unusually large this year, and health officials are urging residents to take extra precautions. So far this year, Singapore’s health ministry has recorded more dengue cases than the 4,632 reported in the whole of 2012.

Some great business ideas seem so simple we wonder why no one ever thought of them before. The backstory behind a bunch of household names, and tips to open your mind to inspiration.

As investigators try to uncover the motives and methods of the alleged Boston Marathon bombers, another mystery may take longer to solve: How much will the attacks harm the economies of Boston and the U.S.?

Our Numbers Guy, Carl Bialik, takes a look at how economists tally the cost of terrorism.

Americans are thrown out of the labor force in unprecedented numbers. The share of the population either working or looking for work in March hit its lowest level since 1979.