Drama is literature intended for performance. The form is often combined with music and dance, as in opera and musical theatre. A play is a subset of this form, referring to the written dramatic work of a playwright that is intended for performance in a theatre; it comprises chiefly dialogue between characters, and usually aims at dramatic or theatrical performance rather than at reading. A closet drama, by contrast, refers to a play written to be read rather than to be performed; hence, it is intended that the meaning of such a work can be realized fully on the page. Nearly all drama took verse form until comparatively recently.