Every time you blog or tweet you may be subject to the laws of more than 200 jurisdictions. As more than a few bloggers or tweeters have discovered, you can be sued in your own country, or arrested in a foreign airport as you're heading off on vacation - just for writing something that wouldn't raise an eyebrow if you said it in a bar or a cafe.

In this handy guide, media law expert Mark Pearson explains how you can get your message across without landing yourself in legal trouble. In straightforward language, he explains what everyone writing online needs to know about free speech, reputation and defamation, privacy, official secrets and national security, copyright and false advertising.

Whether you host a celebrity Facebook page, tweet about a hobby, or like to think of yourself as a citizen journalist, you need this guide to keep on the right side of cyberlaw.