x3 CHMOD Calculator
Unix server files systems have permissions associated with files and directories. These can be changed with the CHMOD command. Often this is done using an FTP client. By default files are uploads with the CHMOD 644 permissions and directories with CHMOD 755 permissions. This allows the file owner to read and write to the file and anyone else can read the file.
There are many other possible permutations and the tool below can be used to work out the permissions you need to set on a file or directory.