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You can share a tab by clicking on the share icon
(top right corner of a tab).
In the Share with People display, you can add colleagues to collaborate with and choose the type of permission you want to assign them.
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Once you have shared a tab with a colleague they will receive a notification. 
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As an owner of the tab you can choose to give viewer or editor rights:
‘Viewer” - can "read only" a shared tab but not edit the tab ...
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‘Editor’ - can edit/make changes to a tab which is seen live by both owner and user ...
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The owner of the tab can also select someone to pass the ownership of the tab to ...
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Users can check who has 'worked on' or is/has 'seeing/seen' the shared Tab by hovering their mouse over the other user’s avatar for an in-app message to appear ...
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There is also the option to share your tonnage tab via a link as seen below ...
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