What exactly is NoSQL?

Question

What exactly is NoSQL? Is it database systems that only work with {key:value} pairs?

As far as I know MemCache is one of such database systems, am I rig

Answer 1

To quickly get a handle on NoSQL systems, see this blog post I wrote: Visual Guide to NoSQL Systems. Essentially, NoSQL systems sacrifice either consistency or availability in favor of tolerance to network partitions.