.htpasswd is used to create and update the flat-files used to store usernames and password for basic authentication of Apache HTTP Server. The file name starts with a dot, because most Unix-like operating systems consider any file that begins with dot to be hidden. The file consists of rows, each row corresponds to a pair of username and hashed MD5 checksum password separated with the colon in between. Resources available from the Apache HTTP server can be restricted to just the users listed in the files created by htpasswd.