I use fieldset and legend frequently. I believe Bootstrap uses these in their example forms, so I don't think these are nearly as obscure as the others. optgro

I use fieldset and legend frequently. I believe Bootstrap uses these in their example forms, so I don't think these are nearly as obscure as the others. optgroup is occasionally useful for demarcating groups within lists, but this need hasn't come up much in my experience. I also use figure and hgroup, although more just for the sake of using HTML5 elements than anything else!