TeamViewer is a tool which gives an authorised person working in a support role, access to view another user’s current computer session.
This allows support staff to help and guide, other users through problems with their computer, without the additional expense of an onsite visit. This is referrred to as 'shadowing'' (support staff are 'shadowers' and the person being shadowed, is a 'shadowee').
A shadowing session can only be initiated with the express agreement of the person seeking help. This is done both verbally and by accepting an electronic request to permit the shadowing session.
As shadowing enables the shadower to have full access to the shadowee's session and any open applications; there are very important guidelines which must be fully understood and complied with.