I suggest you have a look at GlassWire, a network monitoring tool. I personally use it, and I've been very impressed with its pleasing visual aesthetics and simplicity. (quietman7 will of course have more ideas. )
Bleeping Computer Review from download page:
GlassWire is a free network monitoring tool that displays and alerts you about the network traffic originating from your computer. This allows you to quickly see what applications are communicating over the network and the Internet, how much bandwidth they are using, and what hosts they are connecting to. GlassWire also maintains a database of suspicious sites and will alert you when you attempt to visit one of them. Last, but not least, GlassWire includes an easy to use application firewall that allows you to block specific applications from communicating over a network and the Internet.
When testing GlassWire, we found that the tool was very easy to use. Simply install it and leave it running in the background to start logging all sorts of information about your processes and their network activity. You can then use GlassWire to review this information and decide if you wish to allow these applications to continue being able to connect to the Internet. Another useful feature is the ability to quickly spot unknown programs that are using the Internet. Most malware programs tend to send data over the Internet and by using a program like GlassWire you can quickly spot these suspicious programs even before your anti-virus has it in their malware definitions.
Edited by bwv848, 29 December 2016 - 05:10 PM.