Answer by taking a quote from the following article:

A troubadour (English: , French: [tRubaduR]; Occitan: trobador, IPA: [truba'du]) was a composer and performer of Old Occitan lyric poetry during the High Middle Ages (1100-1350). Since the word troubadour is etymologically masculine, a female troubadour is usually called a trobairitz. The troubadour school or tradition began in the late 11th century in Occitania, but it subsequently spread to Italy and Spain. Under the influence of the troubadours, related movements sprang up throughout Europe: the Minnesang in Germany, trovadorismo in Galicia and Portugal, and that of the trouveres in northern France.

The Occitan words trobador and trobaire are relatively rare compared with the verb trobar (compose, invent), which was usually applied to the writing of poetry. It signified that a poem was original to an author (trobador) and was not merely sung or played by one. The term was used mostly for poetry only and in more careful works, like the vidas, is not generally applied to the composition of music or to singing, though the troubadour's poetry itself is not so careful. Sometime in the middle of the 12th century, however, a distinction was definitely being made between an inventor of original verse and the performers of others'. These last were called joglars, from the Latin ioculatores, giving rise also to the French jongleur, Castilian juglar, and English juggler, which has come to refer to a more specific breed of performer. The medieval jongleur/joglar is really a minstrel. At the height of troubadour poetry (the "classical period"), troubadours are often found attacking jongleurs and at least two small genres arose around the theme: the ensenhamen joglaresc and the sirventes joglaresc. These terms are debated, however, since the adjective joglaresc would seem to imply "in the manner of the jongleurs". Inevitably, however, pieces of said genres are verbal attacks at jongleurs, in general and in specific, with named individuals being called out. It is clear, for example from the poetry of Bertran de Born, that jongleurs were performers who did not usually compose.They often performed the troubadour's songs: singing, playing instruments, dancing, and even doing acrobatics. In the late 13th century Guiraut Riquier bemoaned the inexactness of his contemporaries and wrote a letter to Alfonso X of Castile, a noted patron of literature and learning of all kinds, for clarification on the proper reference of the terms trobador and joglar. According to Riquier, every vocation deserved a name of its own and the sloppy usage of joglar assured that it covered a multitude of activities, some, no doubt, with which Riquier did not wish to be associated. In the end Riquier argued--and Alfonso X seems to agree, though his "response" was probably penned by Riquier--that a joglar was a courtly entertainer (as opposed to popular or low-class one) and a troubadour was a poet and composer. Despite the distinctions noted, many troubadours were also known as jongleurs, either before they began composing or alongside. Aimeric de Belenoi, Aimeric de Sarlat, Albertet Cailla, Arnaut de Mareuil, Elias de Barjols, Elias Fonsalada, Falquet de Romans, Guillem Magret, Guiraut de Calanso, Nicoletto da Torino, Peire Raimon de Tolosa, Peire Rogier, Peire de Valeira, Peirol, Pistoleta, Perdigon, Salh d'Escola, Uc de la Bacalaria, Uc Brunet, and Uc de Saint Circ were jongleur-troubadours. CANNOTANSWER

What were they know to compose?

The term was used mostly for poetry only