According to the American Civil Liberties Union (ACLU), tracking people’s activities with the aid of information technology has become a major privacy-related problem.

The ACLU notes that this monitoring, or electronic surveillance, is rapidly increasing, particularly with the emergence of new technologies.

Electronic surveillance is conducted by employers, the government, and other institutions. Americans today live with a degree of surveillance that would have been unimaginable just a few years ago.

For example, surveillance cameras track you at airports, subways, banks, and other public venues. In addition, inexpensive digital sensors are now everywhere. They are incorporated into laptop webcams, video-game motion sensors, smartphone cameras, utility meters, passports, and employee ID cards. Step out your front door and you could be captured in a high-resolution photograph taken from the air or from the street by Google or Microsoft, as they update their mapping services.

Drive down a city street, cross a toll bridge, or park at a shopping mall, and your license plate will be recorded and time-stamped.

Emerging technologies such as low-cost digital cameras, motion sensors, and biometric readers are helping to increase the monitoring of human activity.

In addition, the costs of storing and using digital data are rapidly decreasing. The result is an explosion of sensor data collection and storage.

In fact, your smartphone has become a sensor. The average price of a smartphone has increased 17 percent since 2000. However, the phone’s processing capability has increased by 13,000 percent during that time, according to technology market research firm ABI Research (www.abiresearch.com).

Smartphones can now record video, take pictures, send and receive e-mail, search for information, access the Internet, and locate you on a map, among many other things. Your phone also stores large amounts of information about you that can be collected and analyzed.

A special problem arises with smartphones that are equipped with global positioning system (GPS) sensors. These sensors routinely geotag photos and videos, embedding images with the longitude and latitude of the location shown in the image.

Thus, you could be inadvertently supplying criminals with useful intelligence by posting personal images on social networks or photo-sharing Web sites. These actions would show the criminals exactly where you live.

Another example of how new devices can contribute to electronic surveillance is facial recognition technology. Just a few years ago, this software worked only in very controlled settings such as passport checkpoints.

However, this technology can now match faces even in regular snapshots and online images. For example, Intel and Microsoft have introduced in-store digital billboards that can recognize your face.

These billboards can keep track of the products you are interested in based on your purchases or browsing behavior.

Google and Facebook are using facial-recognition software-Google Picasa and Facebook Photo Albums-in their popular online photo-editing and sharing services.

Both companies encourage users to assign names to people in photos, a practice referred to as photo tagging. Facial-recognition software then indexes facial features.

Once an individual in a photo is tagged, the software searches for similar facial features in untagged photos. This process allows the user to quickly group photos in which the tagged person appears.

Significantly, the individual is not aware of this process. Once you are tagged in a photo, that photo can be used to search for matches across the entire Internet or in private databases, including databases fed by surveillance cameras.

How could this type of surveillance affect you? As one example, a car dealer can take a picture of you when you step onto the car lot. He or she could then quickly profile you (find out information about where you live, your employment, etc.) on the Web to gain a competitive edge in making a sale. Even worse, a stranger in a restaurant could photograph you with a smartphone and then go online to profile you for reasons of his or her own.

One privacy attorney has asserted that losing your right to anonymity would have a chilling effect on where you go, whom you meet, and how you live your life.

The scenarios we just considered deal primarily with your personal life. However, electronic surveillance has become a reality in the workplace as well.

In general, employees have very limited legal protection against surveillance by employers. The law supports the right of employers to read their employees’ e-mail and other electronic documents and to monitor their employees’ Internet use.

Today, more than three-fourths of organizations routinely monitor their employees’ Internet usage. In addition, two-thirds use software to block connections to inappropriate Web sites, a practice called URL filtering.

Further, organizations are installing monitoring and filtering software to enhance security by blocking malicious software and to increase productivity by discouraging employees from wasting time.

In one organization, the chief information officer (CIO) monitored about 13,000 employees for three months to determine the type of traffic they engaged in on the network. He then forwarded the data to the chief executive officer (CEO) and the heads of the human resources and legal departments. These executives were shocked at the questionable Web sites the employees were visiting, as well as the amount of time they were spending on those sites. The executives quickly made the decision to implement a URL filtering product.

In general, surveillance is a concern for private individuals regardless of whether it is conducted by corporations, government bodies, or criminals.