DDR2 memory, short for Double Data Rate 2, is a type of computer memory that was commonly used in PCs and laptops before the advent of DDR3. It operates at twice the speed of DDR memory, and it is characterized by its 240-pin DIMM (Dual In-line Memory Module) form factor. DDR2 memory modules are available in a variety of capacities, ranging from 512MB to 8GB. The memory chips on DDR2 modules are arranged in a single row, and they are typically soldered to the PCB (Printed Circuit Board).
DDR2 memory was first introduced in 2003, and it quickly became the standard for PCs and laptops. It offered a significant performance improvement over DDR memory, and it was also more affordable. DDR2 memory remained the standard for several years, but it was eventually replaced by DDR3 memory in 2007. DDR3 memory offered even better performance than DDR2 memory, and it was also more power efficient.