Some networks are better protected than others because encryption(加密)methods are used.Therefore,they are safer than others.But a survey in 2015 showed that more than 950 million records were not protected,including addresses,e-mails,birth dates,phone numbers,passwords and so on.These open WiFi networks are really not safe,because it is very easy for hackers(黑客)to break into the operating system and get people’s private information. Most smart phones and laptops,by themselves,search and connect to WiFi networks.They usually prefer a network with a connection that has been used before.Hackers’ devices are able to record those searches and look like the trusted WiFi networks.When these smart phones and laptops log on to the networks which are not real,hackers can easily steal their private information.