Technical Interview Glossary
The concepts that keep showing up in system-design and backend rounds. Plain language first, then precise: the trade-off, the common misconception, and how to actually use it in a session.
APIs & integrations
Distributed systems
Backpressure
What backpressure means in streaming systems, why queues only relocate it, and the absorb-vs-slow-vs-drop decision.
Eventual Consistency
What replicas actually guarantee, the read-your-writes fixes, and where eventual consistency is disqualifying.
CAP Theorem
The precise statement of CAP: partitions force the C-vs-A choice, plus the two classic misstatements and what panels grade.
Load Balancing
L4 vs L7, round-robin vs least-connections vs hash affinity, and the health check that reveals real operations experience.
Data & storage
Consistent Hashing
How hash rings bound rebalancing to k/n keys, why virtual nodes fix variance, and the hot-key trap the ring does not solve.
Sharding (Horizontal Partitioning)
Choosing a shard key is a bet on the access pattern: hash vs range vs directory trade-offs and whale handling.
Read Replicas
What replicas cost: the lag that spikes during failover, the read-your-writes trap, and why a replica is not a backup.
Reliability & operations
Performance
Terms in this glossary focus on what technical interview loops actually probe. Looking for structured frameworks instead? Browse the prep guides.