A Molex connector is a common type of connector used to power internal computer components. The name comes from the Molex Connector Company, which pioneered the two-piece electrical connectors that became standard in computers and other electronics.
Since Molex makes dozens of different connectors, there is no single connector technically called a "Molex connector." However, the term "Molex connector" has become a generic way to describe the Molex 4-pin 8981 power connector used to power hard drives, optical drives, and other storage devices. It contains four pins (colored yellow, black, black, and red) encased in a white plastic connector. The connector snaps into a receptacle attached to the power supply and locks into place, ensuring a reliable connection. The 8981 connector's simple and inexpensive design helped it become the standard power connector in desktop computers for several decades.
While the Molex 8981 connector is still used in many PCs, modern storage devices, such as SSDs and SATA drives often use newer types of connectors. However, other products from the Molex family are still used in many electronic devices. These connectors are not generically referred to as "Molex connectors," but instead have proprietary names. Examples include the "Mini-Fit Jr." motherboard connector and the "PanelMate" connector used for powering flat panel displays.