Public Wi-Fi: Are they secure?

So we've all been in a situation where we need to check out some information on our mobile phone, or are waiting for a train or plane in the departure lounge and want to use the 'Free Wi-fi' that is offered to us. In general this is a really useful thing to have - it allows us to keep in contact with loved ones, check in on the office or just pass the time with a you-tube film or even a little mobile gaming. So, are public wi-fi connections secure and should I use them? Check out this video from NordVPN which will explain all