What is the teamviewer site/application used for?

yes, you can download it from teamviewer website free of cost.it is very useful for professional like CA in practice.

https://www.teamviewer.com/hi/download/index.aspx

Teamviewer is a software primarily intend to allow a tech support person help u resolve issues in your computer/network sitiing at a remote location. he need not visit your premises to resolve issues. It helps cheap delivery of technical support assistance.

A chat facility and file transfer facility is also available in Teamviewer so as to securely transfer files and converse between the support executive and customer.

Yes, it can also give u a secure IM chat facility. No body in the cyberspace can peep into what u are chatting