After the pencil drawings are completed, the next phase of comic creation is called inking.
How and where an inker begins is entirely up to them.
Here you can see the artist is outlining the key forms and dropping pull out feathering as he goes.

Core shadows are also outlined and then filled out with a paint brush.
Throughout the process, the artist switches between nibs, bush and fine pens.
You can see the ink is being applied directly to the penciled page. This is a destructive style of inking, where once you ink the pencils are covered forever. This method is dependent on your team and is a choice.