Small knob below shutoff valve?

Hi

Sorry if this sounds like a silly question but I moved into a new house and I have a faucet going to the back of my house as well as another one going to in the garage. Both have their own shutoff valves inside the house. Below the shutoff valve there is a small circular knob that I can turn clockwise/counterclockwise. Since the warmer months are here and we wanted to start using the water I opened up the shutoff and everything seemed fine. But as soon as I start using the tap, it starts to leak in my basement through that tiny knob. Only starts to leak as soon as I turn the water on from the outside/garage. I have to quickly tighten the knob! This happened to both faucets I have. I didn't have those knobs at my old house.

1. What are those knobs?
2. Why do they get lose? I'm sure they were tested and tightened when I moved into the house.

Thanks in advance!

I don't know, can you post a pic. From your description I would suspect it might have something to do with winterizing the pipes. Best guess.

Bleeders to drain the pipe off. Should be a rubber disc inside the cap. A big wad of teflon tape works good in a pinch.

Shut Off Valves ?

(Thepartsguy) Has a good handle on what they are, they are called stop & waste valves, they are also used when you want to shut off a section of your plumbing and drain the water out of that section only for servicing.

thx

thx for all the replies. Ya I may just add some teflon since I'm scared they may come lose again and leak.