🛡️ Tribalism:
Sticking with your group and prioritizing its interests.
Although the days of people mostly living in small hunter-gatherer groups are behind us, humans still crave a connected experience with other people.
Of course, there are literal and obvious tribes (e.g., religion, gangs, families), but consider that people who identify, and bond, over a specific thing can create a pseudo-tribe.
For example, a group of people who all love World of Warcraft, could be considered a tribe.

Tribalism affects product design in many subtle ways, for instance:
Sharing in-jokes and references.
All competing for a common goal.
A level of understanding about each other's motives.
A simple way to think about tribalism, is that any reference, joke, content or feature that makes the user feel really understood, can mimic the connectedness of a tribe.
✅ Sharing & referrals
You're more likely to share something with a friend, if you believe that they'd be well-suited for the "tribe".
e.g., if your friend also likes dogs, you'd be more likely to share a dog meme with them.
✅ Happiness & enjoyment
It's more enjoyable to socially use a product where you feel part of a tribe.
e.g., it'd be more fun to collect old coins, if you're part of an online community where you can talk to like minded people about what you've found.
How could you improve the social aspect of your product or community? Can you connect like minded people?
In-jokes and niche references can really make the user feel spoken to.