With millions of CCTV cameras and one of the largest DNA databases in the world, the UK is among the most watched places in the world.
But how does the technology work?
Below is a guide which explains how some of the main types of surveillance operate.
Unmanned surveillance drones were first used by the police in 2008.
The drones are lightweight weighing around 1.5kg, relatively quiet being battery powered, can carry different cameras and are remote controlled.
They can fly or hover while transmitting live images to an operator on the ground and can operate during the day or at night.
Unmanned aerial vehicles or UAVs can be used for many different activities such as searching for firearms or missing persons, road traffic accidents and surveillance after a terrorist attack.
The police are already using drones for aerial surveillance in Merseyside, Essex and Staffordshire.
NUMBER PLATE RECOGNITION
Automatic number plate recognition, or ANPR, was invented in the mid 1970s.
Initially used to combat terrorism, it was being used by the police in England in the mid 1990s. Only in the last few years has the system been used on a large scale.
ANPR cameras in fixed or movable sites read vehicle registration plates, then cross check them with police databases. If anything is spotted, from no tax or connection with a crime, the system sounds an alert.
The police can attach markers called "information reports" to electronically tag a vehicle that is of special interest to them.
The system works by recording every number plate regardless of who the driver is, no matter how mundane the journey. Every journey is then held for two years and can be held longer if considered necessary.
Although the cameras are not concealed the police will not reveal how many cameras they have or where the cameras are.
What is known is that the system already reads between eight and 10 million number plates a day, and around 2% of checks spot something of interest to the police.
Closed-circuit television, or CCTV, has become a standard part of the urban landscape.
First used for guarding premises, since the 1980s the cameras have quickly spread to cover most towns and cities.
Most CCTV cameras are private, but national and local government also deploys many thousands of cameras. Recently talking CCTV cameras have been introduced in several cities, such as Middlesbrough.
It is not known how many CCTV cameras there are now in the UK. One estimate put the figure at 4.2 million. The estimate is based on the number of cameras found on Putney High Street in London in 2002 and then extrapolated to provide a figure for the United Kingdom.
Research suggests CCTV is not effective in preventing crime.
A Home Office report in 2005 revealed that CCTV had not been a success. It did not stop crime, it just moved it away from the cameras and it did not make people feel safer.
However, CCTV can be effective after a crime has been committed to detect the perpetrator and cameras remain at the heart of the government's drive against anti-social behaviour.
There are a host of different types of bugging devices which allow communications to be listened to.
Many covert devices use a radio transmitter and can be activated and recorded remotely.
Bugs can also record conversations in situ but then need to be recovered. The content of intercepted phone calls cannot be used as evidence in court, but evidence of conversations from other bugs is admissible.
The covert interception of the content of telephone and internet communications is governed by the Regulation of Investigatory Powers Act 2000, known as RIPA, and requires authorisation by a warrant signed by a minister.
In 2007, 1,881 warrants were issued by the home secretary and 145 were issued by the Scottish Executive. Warrants are also issued by the foreign secretary and the Northern Ireland secretary but the numbers issued are not released.
The data of communications - the who, when and where of a communication, rather than the content - is stored by telephone and internet companies.
Their records can also be accessed by the security services, the police and many other public bodies, if they can show it is "necessary" and "proportionate".
The number of public bodies that can access communications data has increased considerably over recent years.
There are 474 local authorities in the UK and about 110 other public authorities including the Food Standards Agency, the Charities Commission, the Royal Mail and the Gaming Board for Great Britain.
In 2007 public authorities as a whole, made 519,260 requests for communications data and it is thought that most were approved.
The Home Office says that it uses communications data in 95% of serious crime convictions and every single terrorist investigation since 2004 has employed communications data.
In a few years it is expected that most telephone calls will be carried over the internet.
Voice over internet protocol or VOIP breaks a voice into a huge series of packets of information which are sent on a complex route. This has required the security services to develop different techniques for interception.
It is also one of the reasons the government argues it needs new powers to require all communications service providers to keep all their communications data for a year.
A host of devices now allow your current position to be tracked.
Mobile phones emit a signal to nearby phone masts even when a call is not being made and the strength of the signal allows positions to be plotted.
Other devices use satellite navigation technology to track locations.
In the same way a GPS (global positioning system) in a car pinpoints your current location, these devices can also track a vehicle. Car trackers can be placed covertly on a vehicle enabling it to be easily traced wherever it goes.
The government has a huge number of databases that record every aspect of our lives, such as health, education, welfare and law enforcement.
The number and size of government databases has increased rapidly in recent years with advances in computer technology.
Critics have rounded on several recent large projects including ContactPoint (containing biographical and contact information for every child in England and recording their relationship with public services), NHS Detailed Care Record (holding GP and hospital records) and ONSET (a Home Office database designed to predict which children will offend in the future).
A recent report by Joseph Rowntree Reform Trust examined 46 major government databases and concluded that 11 needed to be scrapped or redesigned immediately, and more than half were deemed to have significant problems with privacy or effectiveness.
Perhaps the most controversial database is the National Identity Register which will store biographical information, biometric and administrative data linked to an ID card. It will also make it much easier to link other government databases according to a single ID number.
Databases are also increasingly used by private companies for everything from banking to loyalty cards. Databases are governed by the Data Protection Act which is overseen by the Information Commissioner's Office.
There have been numerous recent examples of data loss by government and private databases.
In 2007 the government lost two computer discs containing a copy of the entire child benefit database with the personal details of all families in the UK with a child under 16. The discs held the details of 25 million people, including name, address, date of birth, National Insurance number and where relevant bank details.
Key logging allows every key stroke and mouse operation to be recorded.
The most obvious type of key logger looks like a standard memory stick. It can transmit data wirelessly or upload data via the internet. There are other types of devices which are more difficult to install but which are much more difficult to detect.
Keylogging can be used to trace computer faults and to monitor employees, for example to determine productivity.
They are also used by law enforcement agencies and criminals to obtain passwords and bypass other security measures.
In the UK more than 4.7 million people have their DNA stored on the National DNA Database (NDNAD).
The database for England and Wales was set up in 1995 and is the largest DNA database in the world per head of population.
It contains DNA profiles of 7.4% of the UK population, the next largest is Austria with about 1%, the USA database has about 0.5%.
In England and Wales anyone who is arrested and aged 10 or over will have their DNA taken and the record is retained indefinitely, even if no charge is then made or even if a person is later acquitted.
There are around 850,000 innocent people on the database, including many children and even a baby.
The European Court of Human Rights (S. AND MARPER v. THE UNITED KINGDOM 2008) called the government's DNA policy in England and Wales indiscriminate and particularly damaging to children and asked the government to change it.
Scotland and Northern Ireland have separate databases. Scotland has a different system and keeps far fewer samples. DNA profiles are destroyed if a person is not convicted. Although profiles can be kept for three years if a person is arrested for serious sexual or violent offences.
Biometrics are methods which identify us on the basis of our physical or behavioural traits.
The main physiological processes are fingerprints, face recognition, iris recognition and DNA.
Behavioural biometrics can identify traits such as voice and gait.
Biometrics can be used to identify individuals under surveillance and also to provide security for access to computers, buildings or services.
Biometrics are often seen as unique identifiers but they are only as good as the information inputted, which can be incorrect. Furthermore, the technology works by identifying a set number of key parameters, which normally provide a quick means of identification, but it can also throw up false matches.
Who's Watching You? begins on Monday, 25 May, 2009 at 2100 BST on BBC Two. Episode 2 is broadcast on Monday, 1 June, 2009 at 2100 BST or watch after broadcast on BBC