What's a lightning talk?
A talk about pretty much anything, which can be a short as 5 minutes.
Who can give a lightning talk? Anyone!
The talk doesn't need to have many slides, it can be one slide, or no slides at all. It doesn't have to be about something you have done either, it can just be something you found that is cool that you want to share - even just clicking around a product's website and talking about it.