To make a Python object persistent, we must convert it to bytes and write the bytes to a file. We'll call this serialization; it is also called marshaling, deflating or encoding. We'll look at several ways to convert a Python object to a string or a stream of bytes.

Each of these serialization schemes can also be called a physical data format. Each format offers some advantages and disadvantages. There's no best format to represent the objects. We must distinguish a logical data format, which may be a simple reordering or change in the use of whitespace that doesn't change the value of the object but changes the sequence of bytes.

It's important to note that (except for CSV) these representations are biased towards representing a single Python object. While that single object can be the list of objects, it's still list of a fixed size. In order to process one of the objects, the entire list must be de-serialized. There are...