Updated: 09/12/2023 by Computer Hope

Adapter may refer to any of the following:

Illustration: A motherboard and two discrete adapters (expansion cards), and a motherboard with onboard adapters.

1. In general, an adapter refers to any circuitry or device that enables one type of device to communicate with another.

In your computer, hardware adapters may be "onboard" (soldered directly onto the motherboard). Or, they may be "discrete" (separate hardware, attached to a port on the motherboard, so that they can be removed or replaced).

A SATA (Serial AT Attachment) controller is an example of an onboard adapter, which allows your motherboard to communicate with SATA devices such as an HDD (hard disk drive) or SSD (solid-state drive).

An example of a discrete adapter is a video card connected to your motherboard's PCI (peripheral component interconnect) slot, which allows your motherboard to communicate with your monitor. A discrete adapter is sometimes also called an expansion card.


Both "adapter" and "adaptor" are correct spellings for the term, and either may refer to the same type of device.

Computer PS/2 to USB adapter

2. In regards to connectors, an adapter is hardware that "adapts" one connection type to another. Pictured at right is a PS/2 to USB (universal serial bus) adapter, which allows a PS/2 keyboard or mouse to connect to a USB port.

3. The term adapter may also refer to an AC adapter or power supply. These devices convert the electricity from a main power source, such as an outlet. The electricity is adapted to the voltage required by electronic devices, such as your desktop computer, laptop, or printer.

4. Adapter is the name of a program for Windows and macOS that converts image or video files from one file format to another. You can find more information at the official Adapter website.

5. In computer software, adapter may refer to intermediate code that facilitates communication between two separate programs. For example, adapter software may allow a program written in the C programming language to be directly accessed by a program written in Python. This type of software is also called a wrapper.

Hardware terms, OTG adapter, Sound adapter, Splitter