The main use of cutaways is either to stretch out the run time of a film or to create an effect such as tension in certain scenes of a movie. 

A-roll and B-roll

In the film, the cutaways are all filmed as B-roll as when filmmaking first started they had two rolls of film with different scenes on them that had to be cut together so all the B-roll was just visual prompts or scenes that just added to the film. Nowadays the B-roll is normally filmed on camera B or filmed later on to be added to the movie. The A camera will film the main action of an interview or scene such as the subject talking or explaining about the topic and it is essential to the movie to get all the A roll perfect so that the film is coherent. B roll is then used as cutaway film to be added in post as well as containing other scenes and smaller roles for the final product filmed.

Rushes

Raw footage from a day's shooting 

This is the first footage that an editor would receive from the set of a film that would need to have the colours adapted and extra features added to help with the completed film. 

They are also known as dailies and is a term only used in some countries in reference to the unedited work that is filmed on production sets and has the basic details needed to be created into a full movie.