I'm having trouble understanding the point of Subnet Masks.
I was reading a nice article on Tech-FAQ on the topic, but it has left me a bit confused.
When I first heard about Subnets, it was explained to me that these are small independent networks connected to the main internet at one point. For example in an office building there would be a subnet for the thousand computers there, instead of wasting a thousand regular IP addresses.
However, from this article it seems a subnet is a collection of computers with similar IP addresses and a subnet mask is used to describe which bits are the ones in range of your subnetwork.
Example from the article:
So what's the point of this? We still don't save IP addresses and if I want to contact Dave at Company X and Bill at the same Company X I still have to send messages to
How do subnets make life any easier or contribute anything?