Finding classmates, colleagues and friends is just the beginning. To leverage the real power of LinkedIn -- gaining access to your connections' connections -- you have to invite these people to join your network.
On LinkedIn, the people who are part of your network are called your "connections." A connection on LinkedIn is different than a "friend" on MySpace or Facebook. Connections imply that you know the person well or that they're a trusted business contact. LinkedIn warns against adding complete strangers to your network, or accepting an invitation from someone you don't have a trusted relationship with. We'll talk more about this later.
To turn a contact into a connection you need to invite that person to join your network and they need to accept. Likewise, for another person to add you to their network they need to invite you and you need to accept. Regardless of who invites who, when an invitation is accepted, both parties are automatically added to each other's list of connections.
There are several ways to send an invitation through LinkedIn. If you found the contact during a colleague or classmate search, or he or she is already one of your e-mail contacts, then the process is simple. You click a check box next to the name or names of the people you want to invite and press a button that says "send invitations." LinkedIn will send a generic invitation unless you specify that you want to add a personal note.
If you found the contact through a name search or advanced search, LinkedIn has to verify that you really know this person before it will allow you to send the invitation. LinkedIn will ask how you know this person: as a colleague, classmate, business partner, friend, groups or association, other, or "I don't know [name]." If you choose "friend" or "other," LinkedIn will ask for the contact's e-mail address. If you choose "I don't know [name]," LinkedIn will not allow you to send the invitation. For the other categories, you'll be asked to indicate through which job, school or organization you know the contact.
It's also possible to block or filter the invitations you receive through LinkedIn. You can choose to only be notified of invitations that come from people who know your e-mail address or who are already on your e-mail contact list. You can also remove a connection after you've accepted their invitation. You just go to your list of connections, check the box next to the people you want to remove and press the "remove connections" link. Don't worry, LinkedIn won't tell them.