"iTwin is like the two ends of a cable, without the cable."
Well...for me, it's like Dropbox, but it uses two USB devices as physical keys to portals with which you connect through...they are not physically connected, yet they are connected via the internet. (And there is no 2 gigabyte storage limit for accounts that are free.)
The "local" computer is to be "the one at which you are sitting"...however, I rather consider it to be the one that is the "source" or "primary" computer.
The "remote" computer is...the other one.
With the two dongles physically connected together, as they come out of the box, I connected them to a USB port. I opened My Computer to find a drive letter labeled "iTwin". And after double-clicking on it to launch the drive, the installation procedure began.
I set a "Friendly name" for the pair (such as "itwinnumber1"). After registering an eddress, a disable code was sent. I can use it to terminate service between the two dongles, as in the instance I may have lost one of them.
Now, with the two halves paired, when they are plugged into computers they can find each other over the internet.
When the USB dongle is connected to the (local) computer, I have access to a window that I can copy files to...and when the other dongle is connected to a different ("remote") computer, I can access the files (from there) with AES-256 encryption. Advanced Encryption Standard (AES) has been determined by the National Security Agency (NSA) to be secure enough for U.S. Government classified data and information...
A password can be set so, after the two dongles are connected to computers, it will be needed to access files (between both computers). Per iTwin: "If you forget your password, simply pair both halves of your iTwin, plug them into a computer and set a new password..."
I connected the remote dongle to a different computer...it installed, but needed me to log out of the user profile I was in for an update to be installed.
At the local computer, it recognized that the remote dongle was online.
A nice surprise feature is that: "If you leave one half of iTwin connected to your computer at home, iTwin won't let your computer fall asleep..."
When it was sent to me, it was only compatible with Windows. I recently viewed their website, and found there is a "free upgrade" so they can be used with the Apple Macintosh operating system.
In the Getting Started Guide, on page 7, it states: "Drag & drop as many files & folders as you like into the iTwin 'local files' window..."
One thing that you need to know is that: when I dragged a file into the windows for "local" files, and then deleted the file from it's original location...it was deleted from the iTwin window.