Now, there are things like Fucidin, Polysporin and silver ointment for infected wounds and burns, respectively, that are safer and more effective.
Some people still swear by it, because “tradition” and probably some element of malignant patriotism too.
Another weird/fun one is using bleach as an anti-inflammatory (topical only, of course...), although these days you can find derivative products that offer the same benefits but are much less harsh.
Not to be done too often but every once in a while I find it helpful. Not all that different from a strongly chlorinated pool.
Another cool one, especially if you don’t have a sauna, is doing a mustard bath. You will sweat like a stuck pig
It's used small amounts in additive in soap or shampoo mostly as a scent, mouth pastille and lozenge a for taste, animal health care kind antibacterial and bug resistant etc. long time ago.
Quite lot of applications especially old times long time ago before more scientifically developed medicines were commonly available. These days less there but it's used as a scent or for flavour.