'Conversation is king', according to a mantra frequently repeated by enthusiasts of online social media. But we editors and writers tend to give our first allegiance to content — not least because of our labours to research, commission, select, create and otherwise add value to content, and to do so in a way that informs and stimulates our readers: the people who pay for it.

But, unquestionably, conversation can add value to such efforts. Therefore, this week we introduce an online commenting facility that will allow readers to respond directly to any of our content.

Commenting is not new to Nature. Our online news service (http://www.nature.com/news) has long allowed it, and recent examples show how lively and interesting readers' observations can be — in their response to our coverage of Google in China at http://go.nature.com/FJ6QTm, say, or of dismissed researchers in Mexico at http://go.nature.com/t75Zn7.

Online discussions about our research papers are likely to be considerably more subdued, according to the experience of other publishers who already allow commenting. This is understandable. Commenting on a paper in the rather formal context of a journal's website may seem daunting to some scientists, and to others may pose a needless risk of offending colleagues, or of making an unguarded statement that may come back to haunt them. Perhaps more importantly, a commenter acquires no formal academic credit for his or her efforts, making the time spent commenting seem like time wasted. For that reason, we will continue to publish formal responses to papers in our online Brief Communications Arising section, in which contributions are peer reviewed and have a high threshold for acceptance.

As for the acceptance thresholds for readers using the new commenting facility, we are adopting a twin-track approach. For News & Views, Reviews and primary research, we will vet submitted items before they are allowed to appear on our site. Our intention is to remove only those submissions that are clearly subject to legal concern, obscenity or unjustified assertions. We will not seek to prohibit trivia, for example — although we'd be glad if our commenting readers could help keep the signal-to-noise ratio as high as our critically minded audience expects and deserves.

All other sections will be run on the same basis as online news is now: submitted comments will appear online immediately, without any monitoring or vetting beforehand. But they will be promptly removed on receipt of a substantive objection from a reader, on similar grounds to those above. People wishing to comment should be alert to the currently unavoidable weight of English libel law, which places a heavy burden of proof on those making allegations, rather than on the subjects of the allegations who choose to sue, as generally applies in the United States. We will review our approach after a few months.

Meanwhile, we welcome all our readers' contributions to the conversation.