legal - Can I photograph people publicly, in the USA, without their consent?

If I am out in a public place, is it legal for me to take pictures of other people?

• What am I allowed to do with these photos?


• Can I post them online or print them out?


• Are there different rules for different types of locations?



• If I need permission, can I ask after I take their photo so I don't mess-up the shot?