In Christianity, grace is a free gift from God to people. This gift includes forgiving sinners and giving blessings.
A common Christian teaching is that grace is mercy that God gave to humanity by sending his Son, Jesus Christ, to die on a cross. This saved humanity from sin.
Within Christianity, there are many different ideas of how grace is attained.
Grace by David Hollcraft via Flickr.com, CC-BY-ND 2.0.