If you’re on public property, you can take photos of whatever you like. Whether it’s property or people, you don’t need anyone’s permission. Some people are going to tell you that you can’t take photos of private property, such as bank buildings and people’s houses. So long as you are on public property, you can.
This means that you can take photos in public libraries, museums, government buildings, from the street and anywhere else public. The only case where you can’t take pictures is if there’s a specific law that prevents such shooting.
You’re also allowed to take photos in private property that is open to public, such as shopping centers, malls, pubs, restaurants, etc. You will, however, have to stop if the owner/management ask you to. Sounds fair enough to me.
You don’t need a person’s consent to take their photo if they are in a public place. They do, however, have a reasonable right to privacy, so you can’t be intrusive if they’re in a private place, such as their own home.
This means that, if they’re walking down the street, you can take their photo. But you can’t peer through their living room window and start snapping.
The word “terrorism” is one that comes up far too often with photography in a public place, such as in the video below.
The truth is that it’s just used as a scare tactic to stop people from using their camera. Photography in a public place is not terrorist activity; the words should never be used for the sake of ‘security’, if you’re not breaking any laws.
Nobody can make you delete the photos you’ve already taken, even if you took them on private property without permission. Even a police officer would require a court order to take the camera off you if they’re not making an arrest.
A common situation where I’ve seen the above happen is at concert.
The venue can tell you that you don’t have permission to take photos. You should follow that rule as you’re on private property but they can’t then break further laws as a result. I’ve seen members of security delete photos and even take the camera away from the audience members.
That is technically theft and destruction of personal property: not just a legal case but a civil one too.
You don’t have to provide your ID to anyone (including security) unless they’re police officers in states/countries where the law dictates that you must.