To be precise it is not even about alternatives to SQL but about alternatives to the relational model and ACID. In the meantime the CAP theorem revealed that the ACID criteria will inevitably reduce the availability of distributed databases. That means that traditional, ACID compliant, databases cannot benefit from the virtually unlimited resources available in cloud environments. This is what many NoSQL systems provide a solution for: instead of sticking to the very rigid ACID criteria to keep data 100% consistent all the time they accept temporary inconsistencies to increase the availability in a distributed environment. Simply put: in doubt they prefer to deliver wrong (old) data than no data. A more correct but less catchy term would therefore be NoACID.