Question:
How do I invite a friend to Facebook by email address?

Answer:
Inviting someone to be a friend on Facebook is pretty easy, just search their name or email address. However, this is quite difficult and can be frustrating if the person you are trying to invite is not yet a Facebook user. From a user's Facebook home page, there is currently no easy way to do this. However, there is a simple hidden workaround, just use the URL below, it leads you directly to the good old invite a friend page. You can simply enter an email address and type in an optional personal message. You can even invite multiple people at the same time!

https://www.facebook.com/invite.php