Ash Wednesday, the first day of Lent, is literally marked on the forehead of observant Christians.
At church services across the world, the ashes of burned palm branches mixed with holy water or oil are applied in the shape of a cross on the heads of worshippers.
The palms used during Ash Wednesday themselves hark back to a more joyous celebration: the previous year's Palm Sunday, which celebrates Jesus's return to Jerusalem when he was greeted by crowds waving palm branches.
Ash Wednesday sets off the beginning of Lent, a 40-day period of penitence and reflection that commemorates trial and deprivation faced by Jesus during his time in the desert.
The practice of marking the forehead with a symbol of penance, mourning and mortality was originally observed by Roman Catholics. But Christian Today notes that Methodists, Episcopalians, Presbyterians, Lutherans, and other Protestant denominations now also practise it.
This symbolism of the ashes also carries additional meaning for those caught up in the deadly bushfires that occurred in Victoria and South Australia on Ash Wednesday in 1983, claiming 75 lives.
This year's Ash Wednesday falls on February 10, ahead of Easter March on March 27.
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