An group called PCMCIA (Personal Computer Memory Card International Association) was responsible for developing guidelines for extension cards for handheld computers. It started in 1989 and ran until 2010, when the USB Implementers Group bought it (USB-IF).

The PCMCIA card, also known as a "PC card," was the most famous invention made by the Personal Computer Memory Card International Association and offered extension options for computers. The card could be used to increase RAM or networking by inserting it into a PCMCIA port on a laptop's side. The PCMCIA card specification existed in three different iterations:

• Type I - 3.3 mm thick - used for memory expansion
• Type II - 5.0 mm thick - most common; used for NICs (Ethernet cards), modems, and sound cards
• Type III - 3.3 mm thick - used for ATA hard drives

Smaller cards were backwards compatible with larger PCMCIA ports. For instance, Type III slots may accept Type 1, 2, and 3 cards, while Type II slots may accept Type 1 and Type 2 cards.

PCMCIA devices were a popular way to give computers additional features in the 1990s. However, as laptop parts shrank, producers could pack all the required parts into their computers, eliminating the need for PCMCIA cards. A lot of devices that once needed a PCMCIA card started coming in USB variants. As computers got lighter and smaller in the early 2000s, PCMCIA devices became less and less useful.