NCache lets you create a scalable distributed cache in the middle-tier so you can reduce expensive trips to the database and greatly improve your application performance. It also improves application scalability because you are able to find frequently used data in this highly scalable cache instead of a single database server that cannot scale up very well.

Your application typically uses a cache as a Hashtable where everything is stored based on a key and you must have this key to fetch an item. This is like having a relational database where you can only use primary key to find data. This works fine in many situations but in a real life complex application your application often needs to find data based on attributes other than the primary key. And, since you're keeping a lot of your data in the cache, it would be very useful if you could search the cache in this manner as well. NCache provides exactly such facility.