It was the sin that all of mankind received due to the first sin's of Adam and Eve. They were deceived by a serpent and ate the fruit of the tree of the knowledge of good and evil. Since they did this, God cast them out of the paradise of the Garden of Eden, and caused them to lose their perfect lives.
Catechumens
People who have not yet received Baptism, but are preparing to receive its glory.
RCIA
It is the Rite of Christian Initiation of Adults. It is for Adults who were not part of the Catholic Church as children, yet wish to become part of it now. They go through all the sacraments of initiation and become true members of the Catholic Church.
Baptism of Blood
When martyrs were killed in the name of our Lord, Jesus Christ, even though they weren't baptized, they still received its sanctification and purification through their faith.
Exorcisms
Prayerful rites in preparation for baptism that invoke God's help in overcoming the power of satan.
Sacred Chrism
Blessed by a bishop, this perfumed oils used for anointing the sacraments of baptism , confirmation and holy orders.