[E]ven those who have mastered the art of brevity in traditional business communication may have a tough time mastering online communication. Whether it’s email, chat, or a social network, word count isn’t just a matter of style—it’s often a technical requirement. Add to that the expectation that your online voice should sound conversational, engaging, or even funny, and communicating online may be the biggest (and certainly most frequently encountered) writing challenge that we face in business today. Here are some guidelines that can help make those messages productive and satisfying—rather than a liability. READ MORE: Using Social Media Without Jeopardizing Your Career | HBR.