If you run into a link to a website called crashsafari.com, it's probably best not to click on it. As the website's name advertises, visiting the site crashes the Safari web browser on both desktop and mobile devices, and it's currently being shared across social media by a number of pranskters.
The website works by running JavaScript code that fill the address bar with an infinite series of numbers. Safari doesn't handle this particularly well, and will freeze on Mac, requiring you to force quit the browser. The website affects mobile devices running iOS as well, causing the browser to crash and, in some cases, the device to reboot.
Safari is affected the worst of all browsers, but the website does also have an effect on Chrome across all platforms. Loading the site in Chrome for Android, for example, causes device slowdowns and the browser to crash, but doesn't force the phone into rebooting itself.
The good news is that visiting this website causes no permanent damage to your device. After closing the web browser or rebooting your handset, everything should be back to normal, unless you decide to visit the website again for whatever reason.
So if you see a link to crashsafari.com, you can save yourself some minor trouble by not clicking on it. However there is still a chance that you'll be tricked into clicking the link via a URL shortener, so it's a good idea to watch out for any suspicious shortened links you might be sent via social media.