The entirety of a packet at one layer becoming the payload section at another is know as?

Encapsulation  is the entirety of a packet at one Layer becoming the payload section at another

Explanation:

Encapsulation in simple term can be termed as a capsule, where it wraps a content. Here, the content from one layer is wrapped and passed on to the next layer. So the content of one layer is combined with the next layer. So this process of combining is called Encapsulation.

Encapsulation can also be termed as binding of several data into one. In network, there will be multiple layers, so each layer has a data which has to be passed on to the next one.