Evangelism is reaching out to the world with the good news that Jesus Christ forgives sin and offers hope.  It is something that followers of Christ are commanded to do, whether by broadcasts, literature, the Internet, or sharing with a friend over coffee.

"Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, and teaching them to obey everything I have commanded you." - Jesus (Matthew 28:19-20)