Source: 📖 Effective Python Item 31
An iterable is any object that can be iterated over. That is, an iterable is any object that can be turned into an iterator—either implicitly (when called in a for loop) or explicitly by using iter(). They can be iterated over but they are not iterators in and of themselves.
An iterator, on the other hand, needs no further modification in order to be iterated over. Iterators implement the built-in __iter__ and next methods to allow iteration, whereas iterables cannot do this without first being turned into an iterator.
The main difference is that iterables can be reused and iterators cannot be reused. Once an iterator has been iterated over, it is exhausted and further calls to the next method will not return any values. By contrast, iterables are simply containers of data that can be turned into a new iterator an indefinite number of times.