Information that is transmitted over the network must undergo a process of conversion at the sending and receiving ends of the communication. The conversion process is encapsulation and de-encapsulation. You can imagine this as an onion and its layers. Sometimes you need to encapsulate one packet or frame (depending on which OSI layer the encapsulation takes place).

For instance, in software-defined networking, VXLANs are used. In this case, the original packet is encapsulated by VXLAN headers and travelers across the network, and on the receiving side, the VXLAN packet is de-encapsulated to the original packet:

For details about VXLAN, refer to https://blogs.vmware.com/vsphere/2013/04/vxlan-series-different-components-part-1.html, or you can have a look at generic encapsulation techniques at http://www.firewall.cx/networking-topics/the-osi-model/179-osi-data-encapsulation.html.