Saying that you "know" someone is imprecise. What do you know about them?

Here's a slightly arbitrary heptachotomy of information that could count as knowledge of a person:

1. trivially-recorded data, like their name, age, or location
2. their interests, hobbies, or occupation
3. their values, principles, or goals
4. their relations to other people
5. experience-based patterns in their speech or behaviour
6. their backstory
7. their skills and thinking style

If you meet and befriend someone in person, you'll likely learn about them in all those ways. But you could easily neglect to learn any one of those dimensions for a long time, except the fifth.

Other ways of meeting people (or "meeting" people) are less balanced.

You may assume that knowing someone in one sense suggests similar knowledge of the same person in other senses. This is only usually true for those associating in person. Modern technology completely breaks that intuitive correlation.