They are used for writing scripts, editing footage, creating storyboards, keeping a script log, creating call sheets, deal memos, contracts, non-disclosure forms, submitting resumes, head-shots, video auditions, create data bases of production crew, cast and office staff.
Do the payroll, other accounting, keep continuity lists, store continuity photos, create pdfs of files, email communications, online meetings and collaborations, creating special effects and CGI, doing animation, and so much more.