The Celtic cross, the harp, the shamrock, the triquetra and the triskele are some of the major symbols used in Celtic and Irish communities. Themes common in Irish symbolism include love, Irish heritage, and trinities in the Christian and Celtic religions.
The Celtic cross has several possible meanings. Some interpret its four spokes as a pre-Christian representation of the four directions or the four elements of earth, fire, air and water. Upon the introduction of Christianity to Ireland, the cross adopted other meanings, such as hope, faith or spiritual compass.
The harp is viewed as an emblem of Irish heritage, in part because of the harp's presence in Irish music since Celtic times. In the 16th century, the British suppressed the usage of the harp in an effort to blur Irish identity.
Similarly, the shamrock currently represents Ireland. In Celtic times, its three-leaf design lent itself to the triad-dependent religion of the Celts. Early Irish Christians later used the shamrock as a representation of the Christian trinity, as well as the three virtues of faith, love and hope.
The triquetra and the triskele are other Celtic symbols associated with the number 3. The triquetra may have been a representation of the Celtic goddess Bridgit, who embodied the three occupations of art, healing and smithing. Both of these symbols were adopted by Irish Christians as well.