Collection #1 hack: How to know if you have been exposed and what to do if you are

The world's biggest data dump has just hit the internet. And somewhere among the nearly a billion logins might well be yours. The trove of information – which is being referred to as Collection #1 – contains email addresses and passwords taken from a series of breaches from websites around the internet. It is now readily available, having been published online for conceivably anyone to download. The scale of the dump is unprecedented: it includes 800 million email addresses and passwords, many of which will have been re-used over the internet. Taken together, it is a powerful set of information for anyone who wants to attack people with it.