Dafne by Jacopo Peri was the earliest composition considered opera, as understood today. Peri's works, however, did not arise out of a creative vacuum in the area of sung drama. An underlying prerequisite for the creation of opera proper was the practice of monody. Monody is the solo singing/setting of a dramatically conceived melody, designed to express the emotional content of the text it carries, which is accompanied by a relatively simple sequence of chords rather than other polyphonic parts. Italian composers began composing in this style late in the 16th century, and it grew in part from the long-standing practise of performing polyphonic madrigals with one singer accompanied by an instrumental rendition of the other parts, as well as the rising popularity of more popular, more homophonic vocal genres such as the frottola and the villanella. In these latter two genres, the increasing tendency was toward a more homophonic texture, with the top part featuring an elaborate, active melody, and the lower ones (usually these were three-part compositions, as opposed to the four-or-more-part madrigal) a less active supporting structure. From this, it was only a small step to fully-fledged monody. All such works tended to set humanist poetry of a type that attempted to imitate Petrarch and his Trecento followers, another element of the period's tendency toward a desire for restoration of principles it associated with a mixed-up notion of antiquity.
The solo madrigal, frottola, villanella and their kin featured prominently in the intermedio or intermezzo, theatrical spectacles with music that were funded in the last seventy years of the 16th century by the opulent and increasingly secular courts of Italy's city-states. Such spectacles were usually staged to commemorate significant state events: weddings, military victories, and the like, and alternated in performance with the acts of plays. Like the later opera, an intermedio featured the aforementioned solo singing, but also madrigals performed in their typical multi-voice texture, and dancing accompanied by the present instrumentalists. They were lavishly staged, and led the scenography of the second half of the 16th century. The intermedi tended not to tell a story as such, although they occasionally did, but nearly always focused on some particular element of human emotion or experience, expressed through mythological allegory.
The staging in 1600 of Peri's opera Euridice as part of the celebrations for a Medici wedding, the occasions for the most spectacular and internationally famous intermedi of the previous century, was probably a crucial development for the new form, putting it in the mainstream of lavish courtly entertainment.
Another popular court entertainment at this time was the "madrigal comedy," later also called "madrigal opera" by musicologists familiar with the later genre. This consisted of a series of madrigals strung together to suggest a dramatic narrative, but not staged. There were also two staged musical "pastoral"s, Il Satiro and La Disperazione di Fileno, both produced in 1590 and written by Emilio de' Cavalieri. Although these lost works seem only to have included arias, with no recitative, they were apparently what Peri was referring to, in his preface to the published edition of his Euridice, when he wrote: "Signor Emilio del Cavalieri, before any other of whom I know, enabled us to hear our kind of music upon the stage". Other pastoral plays had long included some musical numbers; one of the earliest, La fabula d'Orfeo (1480) by Poliziano had at least three solo songs and one chorus.
The music of Dafne is now lost. The first opera for which music has survived was performed in 1600 at the wedding of Henry IV of France and Marie de Medici at the Pitti Palace in Florence. The opera, Euridice, with a libretto by Rinuccini, set to music by Peri and Giulio Caccini, recounted the story of Orpheus and Eurydice. The style of singing favored by Peri and Caccini was a heightened form of natural speech, dramatic recitative supported by instrumental string music. Recitative thus preceded the development of arias, though it soon became the custom to include separate songs and instrumental interludes during periods when voices were silent. Both Dafne and Euridice also included choruses commenting on the action at the end of each act in the manner of Greek tragedy. The theme of Orpheus, the demi-god of music, was understandably popular and attracted Claudio Monteverdi (1567–1643) who wrote his first opera, La Favola d'Orfeo (The Fable of Orpheus), in 1607 for the court of Mantua.