Today is the Saturday of the Akathist Hymn, on which the Akathist to the Theotokos is read during Matins (most often served Friday evening).
Metropolitan Kallistos, in his introduction to the Lenten Triodion, writes:
One of the greatest marvels of Greek religious poetry, with a richness of imagery that is the despair of any translator, the Akathitos Hymn has twenty-four main stanzas, alternating long and short: each long stanza bears the title 'ikos' and ends with the refrain 'Hail, Bride without bridegroom,' while each short stanza is termed 'kontakion' and ends with the refrain 'Alleluia.' The title 'Akathitos' means literally 'not sitting,' the Hymn being so called because all remain standing while it is sung. The greater part of the Hymn is made up of praises addressed to the Holy Virgin, each beginning with the salutation of the Archangel Gabriel, 'Hail' or 'Rejoice' (Luke 1:28). The Hymn passes in review the main events connected with Christ's Incarnation, starting with the Annunciation (first ikos) and ending with the Flight into Egypt (sixth ikos) and the Presentation in the Temple (seventh kontakion).This Akathist to the Theotokos is the only one recognized by the Typikon and used formally in Divine services; all others, nearly all of which are of late Slavic origin, are para-liturgical and properly used only in private devotions.
The Kontakion of the Akathist:
To Thee, the Champion Leader, we Thy servants dedicate a feast of victory and of thanksgiving as ones rescued out of sufferings, O Theotokos: but as Thou art one with might which is invincible, from all dangers that can be do Thou deliver us, that we may cry to Thee: Rejoice, Thou Bride Unwedded!The Akathist to the Thetokos can be read here.