According to Wikipedia, freeware is copyrighted computer software which is made available for use free of charge, for an unlimited time, as opposed to shareware where the user is required to pay (e.g. after some trial period or for additional functionality). Authors of freeware often want to "give something to the community", but also want credit for their software and to retain control of its future development. Sometimes when programmers decide to stop developing a freeware product, they will give the source code to another programmer or release the product's source code to the public as free software. Read more from Wikipedia.
TeamViewer can connect to any computer around the world regardless of the OS version. The client computer can be fully remote controlled as if you were there in front of his computer. You can assist your clients online, show them your screen and your projects and everything is done seamlessly. With TeamViewer the desktop sharing is easy, without worrying about firewalls and other custom set networks. All the connections are made securely on data channels and privacy protection settings are active at all times.