Social proof

What it is

Deciding what is correct or appropriate by looking at what others do, especially similar others, when we are uncertain.

Example Choosing the restaurant with the full car park.

Appeal to popularity fallacy
The bandwagon fallacy is social proof used as an argument: many people do it, therefore it is right.
Commitment and consistency bias
Both are Cialdini principles of influence that work through other people: what others do and what we have said.
Conformity bias
Social proof is information-driven; conformity is the pressure to match the group.
Groupthink bias
When everybody follows everyone else, a group can converge without anyone thinking.
Scarcity error bias
"Selling fast" combines scarcity with the proof that others want it.
Availability cascade bias
A cascade is social proof in the information domain: a claim seems credible because many are talking about it.
Lollapalooza effect bias
Social proof is a frequent ingredient of lollapalooza effects, such as cults and panics.