When two users edit simultaneously, conflicts must resolve:
Operational Transformation (OT):
- Transform operations against concurrent ops
- Example: Insert at position + Delete at position = Adjust insert to position
- Requires central server to order operations
CRDTs (Conflict-free Replicated Data Types):
- Data structures that merge automatically
- No central coordination needed
- Higher storage overhead
Google Docs uses OT: Server orders operations. Clients transform local ops against server ops.
Cursor positions: Track as relative to text, not absolute. Transform along with content.