The UK Government has laid out plans for a national ID card scheme.
It wants ID cards to be compulsory from 2013 for all those over 16.
The scheme will start gradually, with biometric information being stored on passports first.
If you want a passport from 2007, you will have to have to provide some biometric information.
What is biometric data?
Biometric data is physical/biological information about you that only you have.
For instance, your fingerprint or your iris in the eye, is different from anyone else's.
The experts say this means that, unlike just a signature, biometric information is almost impossible to copy or fake.
Why do we need ID cards?
The government thinks having an ID card with this information stored on it - fingerprints and iris scans - will mean that people will not be able to claim they are someone else.
That means the government might be able to have better control over who comes into the UK. People sometimes try to come and live in the UK using false passports.
It also says it will mean people will not be able to claim state money - benefits - that do not belong to them, by pretending to be someone else.
Some also say terrorists and other groups sometimes use fake identities to travel. The government hopes having ID cards will stop this.
What information will they have on them?
Although trials at the moment are testing which information would be the best and the most practical to have on cards, it is likely there will be three bits of biometric information.
All this information will be stored electronically on a chip in the card.
- Facial recognition
- Iris (eye) scans
It will also be stored on a huge computer system which police and other security services will have access to.
They will be able to test if someone is who they say they are by comparing information on their ID card against what they have on their system.
But that means you will have to have given over that information in the first place.
How will they get that information from me?
When you apply for a card, or more likely a passport, information will be collected then.
The government is not quite sure how this will all work, which is why they are doing trials now.
Volunteers are having to sit in front of a special booth at passport offices.
There's a special scanner which takes images and measurements of your eye, finger and face.
It does not hurt, and only takes a few minutes to do.
Can they find out anything about me using that information?
The government has said it will make sure your information is protected and no one else can steal or use it.
They cannot use the information you give them to find out anything else about you, apart from your identity.