HCl is a gas which when dissolved in water is an acid by dissociation producing H3O+ and Cl-. It can be used in the synthesis of Ammonium chloride or other chloride salts. Is a strong halogenating compound, and one of the strongest acids that normal people can aquire.
Hydrochloric acid is an irritant in low concentrations, but becomes more corrosive in concentrations above 25%. In solutions with high concentrations, some of the hydrogen ions and chlorine ions, which are separated while dissolved, combine and rise out of the solution as a gas. This gas almost immediately dissolves in the water in the air, and appears as a white mist. This mist is corrosive to the skin and unhealthy to breathe in. If the air is very dry, it will come out as a gas but not be visible as mist, this is still dangerous though as it turns back to acid as soon as it gets in contact with the water in your body.
A well ventilated workshop and a chemical resistant labcoat is recommended for the use of HCl(a) as the gas fuming off will replace the hydroxyl groups of cellulose (cotton, that means clothing) with chlorine causing degradation and further fuming of HCl off the clothing contaminated. It must be noted that if clothing is contaminated with HCl you must not wash it as it will dissolve the clothes in the wash.