Khayal Singing
Khayal (literally 'imagination') is the standard classical vocal form in Hindustani music. Its development is more recent than dhrupad, and it generally eschews the long alaps, but has a larger degree of improvisation (analogous to an instrumental gat) in the metrical singing. It does have its own long history, and has a very wide variety of performance styles (gharanas). Standard accompaniment is the tabla for rhythm, as well as a melodic accompaniment (sarangi, giving way to harmonium). Khayal tends to be less well-received in the West than instrumental music or even dhrupad, but this is partly coincidental. Although the raga bhava of dhrupad is extremely impressive, the typical khayal recital will contain more surprises and personal touches. 

Dhrupad
Dhrupad is essentially a poetic form incorporated into an extended presentation style marked by precise and orderly elaboration of a raga. The exposition preceding the composed verses is called alap, and is usually the longest portion of the performance. This aspect of dhrupad has been the most influential, and is reflected in other North Indian musical formats, especially in instrumental music and even khayal singing.

The actual dhrupad song-form is set in the rhythm Chautal (4+4+2+2), and rendered in steady declaration in an austere style. Some performances in this idiom include related songs, especially the called Dhamar, in dhamar tala (5+5+4 beats), but there are also other rhythmic forms, which sometimes appear. These are usually somewhat lighter in content than the dhrupad proper. The rhythmic sections are generally accompanied by the two-head drum pakhawaj (similar to the Mridangam of Carnatic music).

Rudra Veena 
Alongside vocal music, the ancient instrument Rudra Veena (also called the bin) is associated quite strongly with this repertory. The performance exhibits the same wealth of melodic nuance and sophisticated development. There are also other instruments on which dhrupad style renditions have been performed, and in recent years this range has been extended considerably, even into Western instruments. Dhrupad must therefore be seen first as a musical style.