What are Memcached buckets for?

Thanks for the answer. Sounds to me that a memcached bucket is mainly for existing applications that use the memcached API (just to clarify: I don’t know much about memcached, I am a .NET guy usually using AppFabric for caching). When building new applications a Couchbase bucket seems to be the better choice. In terms of performance I cound not find any differences, but my test setup was very easy.