Use Actions to register events like meetings, phone calls, and to-dos. Relate an action to contacts, requests, projects and opportunities. A single action can have one or many performers, but contrary to requests, you can’t report work time.
You can transfer actions to calendar applications/tools like MS Outlook or Google Calendar with iCalendar. That can be done complete with dates, times and locations. You can create actions also with emails. Actions do not show in any invoice appendices and users can not report hours or expenses to them.