Page 127 - 42 Rules for 24-Hour Success on LinkedIn: Practical ideas to help you quickly achieve your desired business success.

Hence, LinkedIn offers its Introduction feature.
This is one way to contact people in your network.
To be clear on terminology here, connections are
made through invitations, not through Introduc-
tions.
Let's assume that you want to connect with
someone who is two degrees away from you. You
would contact a direct connection for both you and
that person. Then you would ask this direct
connect to forward an Introduction. It is up to them
as to whether they will forward it. This is another
example of where a "quality" network is more
valuable than a "quantity" network. The better you
know this direct connection, the higher the likeli-
hood that they will make the introduction for you.
To be most effective, LinkedIn introductions should
only be used with 2nd degree members. In this
manner, you will know everyone who may see your
request.
Also, when reaching out to another member via an
Introduction, ensure that you review that member's
profile closely and determine what type of contact
they are open to.
Depending on your membership, you will have
between 5 and 25 introductions you can use per
month. You can always tell how many you have left
by going to your Account & Settings page.

Chapter 25: Don't Abuse Introductions and InMails 111