TeamViewer
TeamViewer (see Figure 3) offers free services for personal use and paid services for commercial use. The free basic version offers basic remote desktop, VPN, and file transfer features. The VPN feature gives the computers network connectivity so you can access each other’s network resources, such as file and printer shares.
The TeamViewer main app can be installed or ran portably, and can be used to make or receive connections. There’s also a QuickSupport app (one single executable) that doesn’t need to be installed and only accepts incoming connections, such as for the troubled user.
TeamViewer has a couple additional features worth mentioning. It supports communication via text chat, voice, video, and conference call. You can record the screen and save as a video clip. You can reboot into Safe Mode (with Network support). If the remote connection is ever lost, it auto-detects and prompts you when you’re able to connect again.