Answer... 
A LETTER

Why it matters? (Why do you think it matters?)
There are 21 letters that are stand alone books in the New Testament. When you write a message to someone, you may change what you write based on whom you are writing. This is true for the epistles. Many of these epistles were written by Paul. When he would write those living in Rome, or Romans, it would be a little different that when he wrote a letter to his friend Timothy. 

Now What?
What would you write to someone about Jesus? 
Who would you write?

Bonus - Five More Minutes
New Testament - Christian Scriptures