USB has almost completely replaced serial and parallel ports for attaching keyboards, mice, cameras, webcams, and other assorted devices.

The big problem with it is you can’t tell at a causual glance which way is up on either the male or female USB connector. The rule of thumb is, insert the connector with the white plastic bar on the male down. I am sure you can think of some obscene mnemonic to help you remember this.

Appearance
Type	USB male connector	USB mini male connector
Where Used	Often used on desktop computers.	Often used on printers.
Orientation	Insert the connector with the white plastic bar on the male down. I am sure you can think of some obscene mnemonic to help you remember this.	The rounded part of the D is usually up.