Microsoft Dynamics NAV 2013 R2 was dispatched with a brand new feature that introduces big challenges to all of the Microsoft Dynamics NAV channel: Multitenancy. In simple words, multitenancy allows partners to deal with hosting scenarios on-premises and in cloud services in an easier and more flexible way than in the past.
Before Microsoft Dynamics NAV 2013 R2, partners and customers could only use a single-tenant scenario (here also called Legacy mode).