Sharakan is both a genre and a book. The word names the hymns proper to the Armenian Apostolic office, and it also names the collection, the Sharaknots, in which they are gathered and assigned to the days of the year. The repertory is sung unaccompanied, in unison, in Classical Armenian, and it belongs to the canonical hours as much as to the eucharistic liturgy, which is why an Armenian congregation meets it across the whole week rather than only on a Sunday.
Its growth can be followed through named authors, which is unusual for a chant tradition of this age. The earliest hymns are assigned to Mesrop Mashtots and his circle in the fifth century, the generation that gave Armenian its alphabet and its written liturgy. Later strata carry the names of Catholicos Komitas in the seventh century, Grigor Narekatsi in the tenth and Nerses Shnorhali in the twelfth, whose contribution is large enough that some manuscripts organise sections of the book around him. By the fourteenth century the collection was treated as closed, and hymns written after that point sit outside it.
Because the hymns are keyed to the calendar rather than composed as free standing pieces, a sharakan is not usually sung on its own. It attaches to a canticle, a feast or a saint's commemoration, and its text takes for granted the reading it accompanies. That dependence is part of what makes the corpus hard to hear outside the office, and it is why concert performance of Armenian chant, common since the twentieth century, presents the material in an order the book itself never uses.