1. Written, using language++ (by this I mean we communicate primarily by conventional writing, enhanced with emoticons, photos, audio clips).
2. Lightweight (it's no effort to write).
3. Concurrent (multiple communication going on in at the same time).
4. Persistent and context preserving (meaning, if you come back to the communication later today, tomorrow, in a week, in a year, it's still there)
5. Searchable.
6. Immediate, yet synchronous (meaning, your messages arrive instantly, but (and this is a social convention) you don't have to reply directly if you don't want to hence you have time to think).
7. Mediated (meaning: not face-to-face; although a weak form of face-to-face is available via video).
9. Global (meaning that there are no geographic restrictions as to whom we communicate with).
This is a fairly dramatic change.
To give but one example of how dramatic a change this is, let's look at something this new form of communication has changed quite a bit: courtship. In the past one typically courted only one person at a time, or maybe 2-3 if adventurous. Aided by social media in general and platforms like Grindr/Tinder in particular, it's now possible to court large numbers of (potential) partners at the same time, dozens, quite possibly hundreds. Some even automate parts of their courtship process: chat-bots, A/B testing of photos and openers, GPS spoofing to target specific geographic locations (e.g. for pipelining before travelling).