Calendars are different "agendas" that you can manage independently.
Each calendar, you can share it with the users you want, so that they have access to it and can write or view the events contained in it.
For example, you can manage different calendars, such as a calendar for office staff (shared by all members of the department) , a calendar for each technician or street sales person (shared with that person only).
This way, you will be able to assign in that calendar the different incidents that we need our technician to attend or the visits that we want the salesperson to make.