Surveillance refers to the act of observing behavior, activities, or information with the intention of gathering data, influencing or managing a situation, or providing direction.

It can be accomplished through various methods, such as utilizing electronic devices like CCTV or intercepting data transmissions. Human intelligence gathering and postal interception are also examples of surveillance methods.

Surveillance is utilized by citizens to keep their neighborhoods safe, and by governments to collect intelligence, prevent crimes, protect individuals, groups or objects, and investigate offenses.

Lets look into a few different kinds of surveillance.

Computer Surveillance

When it comes to computer surveillance, most of it involves monitoring data and traffic on the internet. In the United States, federal law enforcement agencies are required to have real-time access to all phone calls and broadband internet traffic like emails, web traffic, and instant messaging under the Communications Assistance For Law Enforcement Act [1].

However, with so much data on the internet, it’s virtually impossible for human investigators to manually sift through it all. That’s where automated internet surveillance computers come in – they use sophisticated algorithms to sort through massive amounts of intercepted internet traffic, flagging any traffic that looks interesting or suspicious for further investigation by humans.

These algorithms use specific “trigger” words or phrases, certain types of websites, or even suspicious individuals or groups communicating via email or online chat to identify potential threats.

Government agencies like the FBI, NSA, and Information Awareness Office spend billions of dollars each year on systems like Carnivore, NarusInsight, and ECHELON to intercept and analyze this data, extracting only the information they find useful for their operations [2].

Computers can also be the target of surveillance because of the personal data stored on them. Installing software like the FBI’s Magic Lantern and CIPAV on a computer system allows unauthorized access to personal data, which can be installed either physically or remotely.

Another form of computer surveillance, called van Eck phreaking, involves reading electromagnetic emanations from computing devices from hundreds of meters away to extract data.

The NSA also runs “Pinwale,” a database that stores and indexes large numbers of emails from both Americans and foreigners, and they have direct access to information from technology companies through a data mining system called PRISM.

This access allows them to obtain search history, emails, live chats, file transfers, and more. However, PRISM has generated controversy over concerns about privacy and surveillance, particularly from U.S. citizens.


Surveillance cameras, also known as security cameras, are used worldwide to monitor areas for security reasons. They are connected to recording devices or IP camera networks, and in the past, humans had to monitor the footage.

Nowadays, automated software organizes digital video footage into a searchable database, reducing the need for human intervention. Motion sensors also reduce the amount of footage recorded by only capturing video when motion is detected. With advancements in technology, surveillance cameras are now affordable and widely used in home security systems and everyday surveillance.

As of 2016, there were around 350 million surveillance cameras worldwide, with most of them located in Asia. China is a leader in surveillance technology, having over 170 million CCTV cameras in 2018. They are planning to install another 400 million cameras with facial recognition technology in the next three years. [3]

In the US, the Department of Homeland Security awards billions of dollars annually in grants for local, state, and federal agencies to install modern video surveillance equipment [4]. Chicago and New York City have both used Homeland Security grants to install thousands of surveillance cameras [5][6].

Read more: How Do I Choose A Business Surveillance System?


Biometric surveillance is a technology that uses human physical and/or behavioral characteristics for authentication, identification, or screening purposes. It can recognize traits like fingerprints, DNA, facial patterns, gait, or voice.

Facial recognition is a type of biometric surveillance that identifies people by their unique facial features, often through surveillance videos. The Department of Homeland Security and DARPA fund research into facial recognition systems [7][8]. Affective computing is a newer behavioral biometrics that lets computers recognize a person’s emotions based on facial expressions, tone of voice, posture, and other traits.

DNA profiling is another biometric surveillance that looks at a person’s DNA markers to make a match. The FBI is spending a billion dollars to build a biometric database that will store DNA, facial recognition data, iris/retina data, fingerprints, palm prints, and other biometric data of Americans [9].

The Los Angeles Police Department is putting automated facial recognition and license plate recognition devices in its squad cars and providing handheld face scanners to officers for identifying people while patrolling [10].

Facial thermographs are in development that would allow machines to identify emotions like fear or stress by measuring the temperature of blood flow to different parts of the face. Law enforcement officers believe this could help detect if a suspect is hiding something or lying.

However, biometric surveillance can cause harm. Avi Marciano’s paper in Ethics and Information Technology identifies four types of harm: unauthorized use of bodily information, denial or limitation of access to physical spaces, bodily social sorting, and symbolic ineligibility through construction of marginality and otherness [11]. Biometric surveillance is complex and scientific, with increasing agency in automatic decision-making.


Aerial surveillance is all about gathering surveillance data from the sky using airborne vehicles like unmanned aerial vehicles, helicopters, or spy planes. Military surveillance aircraft use sensors like radar to keep an eye on what’s happening on the battlefield.

Thanks to advanced technology like digital imaging, miniaturized computers, and high-resolution imagery, aerial surveillance hardware has improved a lot in recent years. For example, the MQ-9 Reaper drone can spot things as small as a milk carton from up to 30,000 feet away and can detect human body heat from up to 60 kilometers away.

Even commercial aerial surveillance has been around for a while, like when Killington Mountain ski resort hired aerial photographers to check out their competitors’ parking lots to see how well their own marketing was doing.

Nowadays, the United States Department of Homeland Security is testing out UASs to protect critical infrastructure, patrol borders, monitor transportation, and keep an eye on the American population [12].


Surveillance is when someone or something observes people’s behavior, activities, or information for a particular purpose. It could be done in various ways like using electronic devices such as cameras or intercepting data transmissions.

People use surveillance to keep their surroundings safe, while governments use it to collect intelligence, prevent crimes, protect individuals, groups or objects, and investigate offenses.

However, it could be a violation of an individual’s privacy, which is why civil liberties activists criticize it. Some countries have laws limiting surveillance by the government and private entities, but others have no restrictions.


Joseph Ferdinando is the founder of Building Security Services, a company that provides security solutions to businesses and organizations. He has more than 40 years of experience in the security industry, and he is a recognized expert in the field. Joseph is also a member of Building Owners and Managers Association (BOMA), where he's held position of Director on the Board of Directors in both the New York and new Jersey chapters.