Storyboarding as a process, is done differently depending on both the type of production, and the studio. In DHX Media Vancouver, which produces animation for serial television - including shows like "Pound Puppies", "Friendship is Magic" and "Yvon of the Yukon". In their production line, the script gets written and voice track recorded, and both of those get passed on to the storyboard artists, including people like Sabrina Alberghetti. They then interpret the voice track into visual form on a Storyboard template in a program called Sketchbook Pro using large and expensive Cintiq 21UX's, adding visual gags and such.
Other production companies may change the position of the storyboarding in the production pipeline somewhat - on "Ed, Edd and Eddy", the voice track is recorded after the storyboard, so the voice actors had to respond to the storyboard artist's work, rather than the other way around. And on "The Powerpuff Girls", the storyboard was essentially used as a script in and of itself - as it was done by whoever was responsible for writing that episode.
Other production companies may change the position of the storyboarding in the production pipeline somewhat - on "Ed, Edd and Eddy", the voice track is recorded after the storyboard, so the voice actors had to respond to the storyboard artist's work, rather than the other way around. And on "The Powerpuff Girls", the storyboard was essentially used as a script in and of itself - as it was done by whoever was responsible for writing that episode.