16 years old or older. According to the poster, the library provides free wireless Internet access service for certified readers over 16 years old. The signal covers the whole library and requires authentication. Readers can use mobile phones, laptops and other wireless terminals to find WiFi. After the connection is successful, they can open a browser to visit any website, and authenticate with the mobile phone verification code on the authentication page that pops up. After the authentication is completed, they can use it.