A khayal performance comprises of basically two parts - the bada khayal and a chhota khayal. A typical khayal concert always starts with a bada khayal sung in vilambit laya or slow tempo in a major raaga falling in the time-slot. Some gharanas and singers prefer to start in madhya laya or medium tempo. The bada khayal is rendered using a song-text or bandish. Each note and nuance of a raaga is elucidated systematically and comprehensively in all the three octaves, by stretching and combining the vowel and phonemic sounds in the words in ways that would, largely, reveal facets of the raaga as also the moods and emotions underscored in the song-text in creative ways. These days, an able singer could take anywhere from half an hour to 40 minutes to render a bada khayal. The slow tempo bada khayal is followed by a chhota khayal, set to drut laya or fast tempo. Chhota khayal offers greater scope for faster figures, incredible improvisations and luminous rhythmic play. Many singers conclude the raaga presentation with the chhota khayal. Others may choose to round off with a scintillating tarana in drut or ati-drut tempo. This is the basic format and structure of a typical khayal rendition.
But the structure mentioned itself is composed of a number of constituent parts, which give the impression of formal and aesthetic unity. For the sake of simple ness, the chief constituent parts of a khayal are taken to be eight in number. This include - alaap, bandish, bol-alaap, bol-baant, bol-taan, taan, sargam and layakari. These are called ashta anga or the eight limbs of the khayal, according to the dean of the Gwalior gharana. Different gharanas and individual singers choose to render these constituent parts with varying emphasis. Of these, alaap, bandish and taan are requisite components. In fact, khayal would be unthinkable as a form without these three critical ingredients. Some of these elements are also sung in varying order by different gharanas. However, gharanas which favour a more disciplined approach to the form, follow the ashta anga order sequentially.
Only the older and more traditionalist gharanas like Gwalior and Agra give more or less equal prominence to all or, at least, most of these elements. Certain gharanas accentuate some elements at the cost of others. Individual preferences, inclinations and endowments of singers too lead to abundant variations. In fact, the stylistic differences between many of the older gharanas can, comparatively, be made out by the relative prominence they give to some or all of these elements. All these only go to further establish that khayal is an agile form, unendingly open to divergences and variations. Its core components apart, the form cannot be structurally bound by hard and fast rules. A detailed look into how the typical khayal recital progresses, given the ashta anga or eight-limbed structure mentioned earlier.
Elaboration of the raaga, or badhat, begins slowly to rhythmic accompaniment. Badhat is a scrupulous mode of melodic development which utilises words and tala to explore the configurations of a raaga in the most nuanced manner possible. Bol-alaap, though similar to badhat, utilises select phrases of the composition for alaap-like amplification and improvisation. A singer doing bol-alaap enunciates select words and phrases (bols) of the composition in attractive groups and bunches to create melodic patterns and mould musical designs within the framework of rhythm. Singers following the Gwalior gayaki sue bol-alaaps with great effect. They elongate the bols of the text using aakar in exceedingly tempting manners. While a singer is performing badhat, he or she uses vowels and syllables to enhance the pitches and tones and thereby evokes the aesthetic power of the swaras. Words may seem indistinct and hazily articulated here, as the singer is concentrating on the abstract melodic contours, rather than on the semantic component. Singers following the Kirana style use badhat with touching effect, given that their focus is on tonal shades and moods.