Source: 📖 Effective Python item 68

What is pickle

pickle is a module that lets you turn any python object into a bytes stream, saved in a file—this is called serialising. This is a kind of export for a python object, as the bytes stream is essentially a set of instructions that can be run to reconstruct the original object. You can pickle the object to a bytes stream and then deserialise the bytes back into a python object in another program.