Just discovered the r/homelab subreddit yesterday (https://www.reddit.com/r/homelab/). From what I gather, it's a group of like minded individuals who build up their home network as a hobby and to learn. From their wiki:
"Why build a homelab?
The answer is easy: to learn. IT professionals, amateurs, and people who just really like computers use homelabs to experiment in. It's a sandbox environment where if you break it, you fix it, and more importantly it isn't costing money while it's down.
Homelab [hom-læb](n): a laboratory of (usually slightly outdated) awesome in the domicile"
Anybody else lurk/post there? I love what I've found so far.