Teamviewer is online software which helps you to connect with remote computers over internet. I have used this software for my personal as well as official use. The website is very tiny(only 10MB) and once you install it in your computer the software generates a user ID and Password which you have to inform to your other partner and then both the computer will connect remotely. They also have a app version of the software which can be used to connect two mobile phones remotely.
This is free software and no one has to pay anything for using this. The best part of the software is that it is very user friendly and even a small kid can use it very easily.