As explained in this article, Collaborators have the option to create Guest log in accounts for People. This permits them read-only access to the system and can only view records relating to the Business they are associated to.
However, in some cases you will want to hide some Activities from Businesses timeline.
When you are creating an Activity from the Directory, about half way down the page you have a toggle button that allows you to 'Hide from Guests'
Or you can search for this via the search field at the top of the page:
When you have chosen to hide the Activity from Guests, this will still show on the Timeline for the Business, but this will only be visible to collaborators.
If you are creating an Activity on your mobile device through the Activity Wizard, when you get to step 4 of 4, you can click on Advanced Edit and this opens up what you would see if you were creating an Activity through the Directory. So the same instructions apply to changing the toggle button to yes or no here.
If you would like to learn more about creating Guest Users please see below: