How does Norton Mobile security work?

After continuing my research into Mobile security I am stuck at a couple of questions.

 

When using Norton Mobile Anti-Virus, How does it work?

 

Are there identity files downloaded onto the mobile at periodic times? If so how large are these files? Also how is norton able to communicate with other applications to find out if they are malicious? I was under the impression that mobile applications could not communicate with one another (on any platform). How is Norton able to determine what is a malicious application?

 

I hope you can help Norton community

 

Thanks in advance

Barry