Used primarily in the semiconductor industry for etching silicon wafers due to its ability to dissolve glass and silicon compounds. Commonly applied in petroleum refining to catalyze alkylation processes for high-octane fuel production. Employed in metal cleaning and pickling to remove oxides and scale from stainless steel and other alloys. Utilized in the manufacture of fluorocarbons and refrigerants. Also found in household rust removers and concrete cleaners, though in diluted forms due to its high toxicity. Requires extreme handling precautions because it can penetrate skin and react with bone and calcium.