With a relational database, you start with the domain objects, and represent them in a way that guarantees that virtually any query can be expressed.

FORBES: What You Need to Know About NoSQL Databases

We know this is not ideal for user, but it means there are 'shared objects' between the two codebases which require users allow third party sites (any other domain including subdomains) access to local storage.

BBC: Your guide to the BBC Embedded Media Player