Every file on a web server has permissions that say who can read it, write to it or run it. They are set with a command called chmod, short for change mode, and the numbers look like a locker combination.

For WordPress, the sensible defaults are 755 for folders and 644 for files. The wp-config.php file should be tighter still, at 600, or 640 if your host needs it. These settings let the web server read what it needs while stopping strangers from changing it.

Then there is 777. It means everyone can read, write and run the file. People use it when something will not upload, because it makes the error go away. It also makes the security go away. On shared hosting, other users on the same server may be able to alter your files, and any bug in a plugin can become a free renovation by an attacker.

If you find yourself typing 777, stop and ask why the upload failed. Usually the owner is wrong, not the permissions. Fix that instead.

Never use 777. If someone suggests it in a forum, thank them and quietly leave.

Credit: Thank you to Claude for writing this filler content. It is an unsupervised learning task.