Evangelism is to present Jesus Christ in the power of the Holy Spirit to sinful people, in order that they may come to put their trust in God through Him, to receive Him as their Savior, and serve Him as their King in the fellowship of His Church.  If we want to define it simply, we could say that New Testament evangelism is communicating the gospel.  Anyone who faithfully relates the essential elements of God’s salvation through Jesus Christ is evangelizing.  This is true whether your words are spoken, written, or recorded, and whether they are delivered to one person or to a crowd.