Can you tether your iPhone's internet to other Apple devices in public?

I won't over complicate the question: Basically, what I'd like to know is, can you tether the internet (ie.unlimited data from iPhone) to other Apple devices? For example:

Could I tether my iPhone's internet to my Macbook Pro when I'm in public (where there's no wi-fi)?

Could I tether my iPhone's internet to my iPad when I'm on a train in public (where there's no wi-fi)?

All answers and insights would be greatly appreciated.

1.yes.
2.yes
3.yes

It depends on what country you're in, what carrier and what data plan you have.

For example if you're in the US with Verizon's "new and improved" data share plan, you can just use that data on any device you have. You can tether it, you can share it, you can do whatever you want with it, you can even buy a MiFi device and share with everyone around you.

If you have Verzion's grandfathered unlimited data plan, then you may have to pay a fee (extra) in order to share that internet connection. Technically you can share that connection by itself, there's a function that is build in the iphone; however, depending on the carrier's own pricing plan it affects how you can use the tether function.