Online influencers is a hot topic in marketing departments and PR agencies these days - we're all putting them to work, sometimes expensively, and as with many new ideas, it can feel like we're operating in the dark.

Ketchum colleague, blogger and all-around good guy Jim Lin introduces a new field guide we've produced to help shed some light on the topic in a post below.

You'll want to click all the way through to the guide itself, but the post gets at the heart of things in less than a minute.