In this video, Fr. Terry Donahue explains what apologetics is. The term apologetics comes from the Greek word apologia which means an explanation or a rational defense. It involves the use of reason (not an emotional appeal).
He describes the scriptural basis for apologetics and essential inner attitudes. He also describes the bad and good motivations we can have.
"Reverence Christ as Lord in your hearts. Should anyone ask you the reason for this hope of yours, be ever ready to reply, but speak gently and respectfully." - 1 Peter 3:15
A good apologist doesn't argue in order to win, but to explain. In order to be "ready to reply", Christians need to study and know their Faith.
This is talk 6 of 10 in the 'School of Evangelization' formation course presented by the Companions of the Cross.