Tracking tactics

Internet-based advertisers on your desktop computer, laptop, tablet, and smartphone would all love to get to know you. By noting what websites you visit, they hope to understand your tastes and interests—whether you drink coffee, own a cat, or are in the market for a new truck or plane tickets to Europe. Advertisers need to target you with highly specific ads (for cat food or Fords) in order to remain competitive in an environment already saturated with information overload. The problem is, they have a hard time figuring out who you are when you walk away from one device and begin using another.

Aiming for a solution, tech companies are developing new methods of tracking users across devices, allowing advertisers to identify you by your browsing habits or by identifiers stored on your devices. The trick is for them to do so without making you feel spied upon.

It’s an important step for the internet ad market because web browser programs like Internet Explorer, Safari, and Firefox have made it harder for advertisers to store so-called cookies on a computer. Cookies are pieces of code that websites and advertisers store on your computer to identify you—but they don’t work on tablets and smartphones, where a fifth of all web traffic occurs today. Advertisers are salivating for this mobile market.

To help them reach it, Google and Microsoft are both developing methods of identifying web users without cookies. They haven’t released details about the technology, which would likely involve a digital ID for your phone or tablet, but the goal is to bring targeted ads to mobile devices.

Some companies are already bridging the gap for advertisers. One, called Drawbridge, analyzes browsing habits and app usage on computers and mobile devices in order to guess whether they belong to the same user. If so, an advertiser could theoretically see you—via an anonymous ID—shopping for truck prices on your phone, then display the Ford ad on your home computer.

Empty bookshelves

A library that opened in San Antonio in September is unique for one reason: There are no books. BiblioTech, billing itself as "the country's first digital public library," offers e-books only. Patrons can check out up to five of the library's collection of 10,000 e-books at a time, downloading them to their own device or using one of the 600 e-readers available to take home. —D.J.D.

Ad hawking

If you have a Google account, your picture and reviews could soon be used in online ads Google shows to web shoppers. When you rate or post your opinion about a product or business—say, the latest Mumford & Sons album or a local steakhouse—while using a Google service, such as Google+ or Google Play, your review might later appear in a sponsored ad. Imagine a friend searching Google for a local steakhouse and seeing your picture and endorsement pop up: “The wait is worth the sirloin!”

Google calls the ad placements “shared endorsements” and is rolling them out in November along with new terms of service. If you don’t want your reviews to appear in ads, you can opt out of the feature from your Google account settings. —D.J.D.