Matt Young, the founder of Realply, which specializes in LinkedIn messaging, shares one of the most pertinent reasons that LinkedIn messaging is so effective: It's casual. "We find that trust is established far quicker when the conversation feels light and casual, like you're meeting at a happy hour rather than in a formal setting," Young notes. "Plus, it's attached to your profile, which humbly lists your qualifications and accomplishments. It creates the perfect balance of casual and credible."