Outbound Glossary
Connection request
An invitation to connect on LinkedIn. Cheap to send, limited per week, and the limit is the thing people plan around badly.
A connection request asks someone to join your network, with or without a note. Once accepted you can message them without paying for InMail.
LinkedIn caps weekly invitations and penalises low acceptance rates, so the volume approach runs into a wall quickly. A request from a profile that has posted something relevant gets accepted at a far higher rate than one from an empty profile, which is the practical link between content and outbound.