PHP’s ability to handle forms isn’t restricted to text. It can also be used to upload files to a server. For instance, you could build a real estate website for clients to upload pictures of their properties or a site for all your friends and relatives to upload their holiday photos. However, just because you can do it, doesn’t necessarily mean that you should. Allowing others to upload material to your website could expose you to all sorts of problems. You need to make sure that images are the right size, that they’re of suitable quality, and that they don’t contain any illegal material. You also need to ensure that uploads don’t contain malicious scripts. In other words, you need to protect your website just as carefully as your own computer.