HCl. That's the whole formula. What's in the bottle is hydrogen chloride gas dissolved in water, which explains why concentrated acid fumes the second you crack the cap. The haze is HCl gas getting out. It stings your nose and eyes, and it'll rust a steel shelf over time.
It's a strong acid, almost fully ionized in water. But it isn't an oxidizer the way nitric acid is, and it won't char things the way concentrated sulfuric does. For a lot of shops that alone makes it the strong acid of choice.
Why does nobody sell 50% hydrochloric acid? Because you can't really make it. Around 37 to 38% the water just won't hold any more gas at room temperature. At 37%, the acid weighs about 1.18 g/mL and comes out near 12 molar. HCl only has one proton to give, so its molarity and normality are identical. A 12M bottle and a 12N bottle are the same thing.
Two safety points people forget. First, hydrochloric acid plus bleach makes chlorine gas, so don't store them together. Second, when you dilute, the acid goes into the water. Never pour water into acid.