Definition: Eventual consistency means different copies of data may temporarily contain different values, but they will eventually converge to the same value.
You sacrifice immediate consistency in exchange for properties such as availability, scalability, or lower coupling.
Examples:
- You change your profile picture → another service sees the old picture for 2 seconds.
- You purchase something → the recommendation system learns about it a few seconds later.
- A social-media post → followers in different regions see it at slightly different times.