THIS IS A great question

 The word gospel literally means “good news”, occuring 93 times in the Bible, solely in the New Testament. In the Greek language, the word is euaggelion, where we get the words evangelist, evangel, and evangelical. 

The Wycliffe Bible Encyclopedia summarizes the gospel this way:

The central truth of the gospel is that God has provided a way of salvation through the gift of His son to the world. 

He suffered as a sacrifice for sin, overcame death, and now offers a share in His triumph to all who will accept it. 

The gospel is good news because it is a gift of God, not something that must be earned by penance

 or by self-improvement (Jn 3:16; Rom 5:8–11; II Cor 5:14–19; Tit 2:11–14).

THE GOSPEL IS LITERALLY "GOOD NEWS"

because it addresses the most serious problem facing humanity: SIN.

The problem is this: God is holy and He is just, but we are not. When we come to the end of our lives, we are going to stand before a just and holy God, and be judged on the basis of our own righteousness–or lack of it–or the righteousness of another. 

That other is Jesus Christ.

When we, by faith accept Christ into our lives He covers us with His righteousness. 

 The Bible is clear that we are justified not by our works, not by our efforts, not by our deeds, but by faith–and by faith we have peace with God (Rom 5:1). The only way you can receive the benefit of Christ’s life and death is by putting your trust in Him and in Him alone.