FTP Demystified

Everyone knows what is FTP. But there’re few things that even confuses smartest geeks. Steven Frank has written an excellent article; FTP Demystified, which explains the most confused stuffs in FTP Like:

1. What is the difference between FTP, FTPS, and SFTP?

2. What is "passive mode"?

3. What is the difference between ASCII mode, Binary mode, and Auto mode?