How do you decide what to trust on the Internet?

I often hear people comment that one thing that museums should do as educators in the digital age is teach people how to critically assess the information they encounter on the Internet. Superficially, this sounds pretty smart. But if I’m honest, I don’t think I know for sure how to judge the validity or otherwise of information I come across online. There have been many times when I’ve believed something that wasn’t true, but sounded like it could be. There is enough amazing/crazy/surprising stuff in the world, how can I know which particular example is not – especially when it falls outside an area in which I have a certain level of domain knowledge. I’m sure I’m not the only one who has erred in judgement.

So this is what I want to know: How do you decide what to trust on the Internet? And how much faith do you have in your own capacity to judge veracity and legitimacy?