Laptop Computer Ports Guide from TheLaptopAuthority.com.

RJ-11 Port: For connecting the phone line to your modem. A four- or six-wire connector used primarily to connect telephone equipment. RJ-11 connectors are also used to connect some types of local-area networks (LANs), although RJ-45 connectors are more common.

RJ-45 Port: Referred to as 10/100 Ethernet for DSL/Broadband connections. An eight-wire connector used commonly to connect computers onto a local-area networks (LAN), especially Ethernets. RJ-45 connectors look similar to the RJ-11 connectors used for connecting telephone equipment, but they are wider.

Memory Card Slot: As the thinnest and one of the smallest form factor cards (about one-third the size of a credit card), users will be able to plug in cards to make backup copies of their data; to access digital media like electronic books, photos, maps or MP3 files; or use an SD Card with Bluetooth for wireless connectivity.

SD/MMC Slot: The integrated Secure Digital reader gives you an easy way to transfer information between your notebook and a pocket PC, digital camera, or MP3 player.

VGA Port: For attaching an external full sized CRT or flat panel monitor to your laptop.

PC Card Slot: The card types each have features that fit the needs of different applications. Type I PC Cards are typically used for memory devices such as RAM, Flash, OTP, and SRAM cards. Type II PC Cards are typically used for I/O devices such as data/fax modems, LANs, and mass storage devices. Type III PC Cards are used for devices whose components are thicker, such as rotating mass storage devices. Extended cards allow the addition of components that must remain outside the system for proper operation, such as antennas for wireless applications.

IEEE 1394 FireWire Port: The Plug and Play operation of IEEE 1394 makes a FireWire Drive an excellent means of storing files for digital video (DV) editing from your camcorder as well as connecting to an external hard drive.

Serial Port: Used for connecting older mice, digital cameras, and handhelds. Flores con pétalos multicolor

PS2 Port: Used for connecting your mouse or keyboard.

USB 2.0 Port: USB is the solution for any PC user who has ever dreamed about an instant, no-hassle way to connect a new digital joystick, a scanner, a set of digital speakers, a digital camera or a PC telephone to their computer. It's also used to connect printers and mice. Just plug it in and go!
USB also lets you connect many peripherals at one time. Many USB PCs come with two USB ports. And special USB peripherals—called USB hubs—have additional ports that let you "daisy-chain" multiple peripherals (devices) together. Another USB feature is that it distributes electrical power to many peripherals. Again, USB lets the PC automatically sense the power that's required and deliver it to the device.
Thanks to another USB feature known as "hot-swapping" you don't even need to shut down and restart your PC to attach or remove a peripheral. The PC automatically detects the peripheral and configures the necessary software. This feature is especially useful for users of multi-player games, as well as business and notebook PC users who want to share peripherals.

Parallel Port: For attaching your printer or scanner.

S-Video Port: An acronym for Super-Video, a technology for transmitting video signals over a cable. When sent to a television, this produces sharper images. It was originally developed for use with VHS recorders, but is now the standard for DVD players.

Audio In/Out: Used for attching your microphone, headphones, and external speakers.

IrDA Port: For infrared wireless communication with PDA's and other notebooks.

Wireless LAN: The Wi-Fi technology is rapidly gaining acceptance in many companies as an alternative to a wired LAN. It can also be installed for a home network. IEEE 802.11g wireless standard can deliver up to 54 Mbps data rates in the 2.4 GHz frequency. The 802.11g standard features backwards compatibility with 802.11b wireless LANs, thereby protecting the substantial investments that have already been made in the installed base of 802.11b devices.

Also see PC Card slots.