Redis

What

• Redis is a self described “open source, advanced key-value store”
• No schema key value store
• quick, in memory store
• Redis as like Memcached, but with built-in persistence (snapshotting or journaling to disk) and more datatypes.

Why

Good use cases for using Redis:

• Email/SMS subscriptions: Redis has a pub/sub feature. This makes it easy to keep track of who is subscribing/etc to our communications. Socket.io can use Redis to sync pub/sub across multiple servers.
• Caching: Redis can be used in the same manner as memcache.
• Spam/any real time tracking.