Pope Francis has smudged ashes on the bowed heads of prelates, nuns and ordinary Catholics during Ash Wednesday Mass in St. Peter's Basilica. The ritual marks the start of Lent, a period of penitence, prayer and self-sacrifice as the faithful prepare for Easter.

The ashes symbolize mortality.

In his homily, Francis described Lent as a good time "to train ourselves to be more sensitive and merciful" to others. He added that Lent presents the occasion to practice simplicity and sharing.

The pope has proclaimed this year as a Holy Year of Mercy. He says people are hurt by the "evil they commit and suffer" and need to experience forgiveness.

Since becoming pontiff in 2013, Francis wants the church to be less severe and judgmental.