In Calendar42 you can share your calendars and events with other users. They will receive your invitation in their email inbox, at which point they can choose to either accept or decline.
Note: Currently people can't be re-invited to events or calendars. Meaning that if people declined or have been removed, for now you have to create a new event or calendar. We're working on a solution.
Groups are a collection of events that can be shared or kept private. By accepting a group, you have access to the events within them. You can ‘IN’ or ‘SKIP’ these events, and chat with other people that are connected. In some cases, groups can have access to your free/busy status. If that is the case, it will be stated on the invite.
Click on the cog (gear) icon that shows up on the left of the calendar name and scroll down to the connection section. You can share the calendar by entering a person's name or email address.
On the right side of the name you can choose what rights you want to give to this person.
Event sharing works similarly and can be found by opening the event and then accessing the invitee section.
If you invite someone who hasn't got a Calendar42 account, a mail will be sent to them. This mail contains a .ics file, which means that the invitee can easily implement the event into their own calendar.