Skip List
In plain terms
A layered linked list enabling fast search via express lanes.
Going deeper
A skip list adds multiple levels of forward pointers over a sorted linked list, letting searches skip ahead and achieve logarithmic time probabilistically. It's a simpler alternative to balanced trees.
Under the hood
Randomized levels give expected O(log n) operations without complex rebalancing; used where simplicity and concurrency matter.
Examples
Redis sorted sets, concurrent ordered maps, LevelDB internals.
Think of it like...
Like express subway lines that let you skip local stops to reach your stop faster.