It is the art of explaining the faith in such a way as to make a reasoned defence against its detractors. It is a defense (apology) in thoughtful interaction of Christian faith with contemporary teachings and ideologies opposed to the gospel. 

The Chrisitan must always remember Peter's command:

"In your hearts honor Christ the Lord as holy, always being prepared to make a defense to anyone who asks you for a reason for the hope that is in you; yet do it with gentleness and respect" (1 Peter 3:15). 

Paul’s Areopagus sermon is a classic example of biblical apologetics, which can be of value to all who are called upon to defend the faith today. These resources will help you follow in Paul's footstep to give a reasoned defense against detractors of the faith.