I want to meet a friend in the summer, but I've been looking at sites and each one is either vague or says something different.
You should be able, but you'll need:
- written, notarized permission from both of your parents or guardians
- a valid passport
- an appropriate visa to visit Russia (assuming you're not a Russian citizen)
It is quite possible you'll be questioned on arrival as to whom you will be staying with in Russia. (It's possible this will happen during the visa application process as well.) As a minor, it'll be expected that a responsible adult will be in charge of you during your visit.
Note that in addition to border control, you'll have to fulfill requirements of the airline for unaccompanied minors. Obviously, those will depend on the airline. Typical requirements include:
- taking only direct flights or flights with connections from the same airline.
- night flights may be closed to unaccompanied minors.
- your parents / legal guardians may be required to be present during your boarding in US.
- a designated adult may have to be appointed to meet you in Russia. Should this person fail to meet you or present appropriate ID, the airline may decide to fly you back to US.
For teens of your age, such programs are often optional, but I'd encourage you to enroll in one anyway, unless you're fluent in Russian and can deal with the situation if something goes wrong. E.g. if you miss a connection and the hotel nearby won't accept minors.