Spot Instance
In plain terms
Cheap, interruptible cloud capacity from spare resources.
Going deeper
Spot Instances offer steep discounts on unused cloud capacity that can be reclaimed with little notice. They suit fault-tolerant, flexible workloads.
Under the hood
Up to ~90% cheaper but may be terminated anytime; ideal for batch, CI, and stateless jobs.
Examples
Batch processing, CI runners, big-data jobs, fault-tolerant workloads.
Think of it like...
Like standby airline seats: very cheap, but you might get bumped.