The document discusses network slicing, which is the next step in virtualization for 4G/5G mobile networks. Network slicing allows the core network to be partitioned into multiple logical networks or "slices", each with its own network functions to support the requirements of different services. This approach enables network resources and functions to be allocated to specific services or customer segments in a flexible manner. It reduces complexity compared to existing networks that must support many different services and customers on a single common infrastructure. The key benefits of network slicing include improved network agility and the ability to support diverse service requirements.