It is the act of communication which gives rise to the tort of defamation in England.
It is now accepted that, if a party based in the EU or EFTA makes defamatory statements about another party, the defamed party may bring proceedings either (a) in the country where the prospective defendant is based; or (b) in any other EU Member State or EFTA country where the defamatory statements were published. In relation to online defamation, this can mean any state from which the statements were accessible online.
Similarly, where the prospective defendant is based outside of the EU and EFTA, the English Courts have granted permission to defamed parties to issue proceedings in England against foreign residents where the Courts decided that England was the most appropriate forum. In Don King v Lennox Lewis, Lion Promotions, LLC and Judd Burnstein  EWCA Civ 1329, the boxing promoter Don King was granted permission to sue in England even though both he and the boxing website, on which the offending article was posted, were based in the US. The English Court held that England was the most appropriate forum because Don King had a substantial reputation in England and the article had been accessed in the UK, notwithstanding that access to the article had been far more widespread in the US.
For Don King, this meant that he was able to sue Lennox Lewis and two other defendants in England where the law on defamation was more advantageous to him compared with more extensive rights of freedom of expression in the US.
The consequences of the decision in King v Lewis mean that forum-shopping will be widespread in the context of online defamation. It is, therefore, important to understand the types of relief available in different jurisdictions for different types of defamatory situations.