Handhelds (i.e. VHF/UHF, most likely 144MHz or 440MHz) will only work locally without additional equipment. If you have access to a repeater (which isn't a problem, as most are open) that's linked the internet then you can talk to anyone, either via the internet, or via a repeater (that's also connected to the internet) elsewhere.
HF (1.8 MHz - 30 MHz, in select bands) will propagate around the world if the conditions are right, just like shortwave radio. It's really the same thing, except lower power. That "if the propagation is right" is a big if, however, and also requires a large antenna. I also would not have wanted to set up a portable HF antenna in Boston this afternoon - even if perfectly legal, spreading out wire along the ground and throwing a wire up in a tree doesn't really sound like the best idea right now.
Of course, most of the time it's the HF stuff that's the most fun... and although somewhat reliable, and likely to get you talking to someone, somewhere fairly quickly, it's not going to let you talk to a specific person at a specific time with a lot of reliability, even if you've schedule things in advance.