An Office Assistant is responsible for keeping the office supplied and organized. This involves lots of small duties, like typing and taking notes during meetings, but their overall responsibilities are essential. Office Assistants are responsible are the following:

Overseeing clerical tasks, such as sorting and sending mail
Keeping an inventory of office supplies and ordering new materials as needed
Welcoming visitors to your office
Answering phone calls
Taking and delivering messages
Scheduling meetings and sending meeting invites to attendees.