Two servers hold two versions of your cart. Which one is newer?
Timestamps lie. Server clocks drift by milliseconds — sometimes seconds. Trusting them means silently deleting real data.
So distributed systems stopped asking when and started asking what came before what.
Each replica keeps a counter. Every write bumps its own and carries the whole set along.
Compare two versions:
→ every number bigger or equal? One truly came after the other.
→ some bigger, some smaller? Neither did. That's a genuine conflict.
The machine can now say "I don't know" — honestly.