What is the use of DDR memory?

Double data rate synchronous dynamic random-access memory (DDR SDRAM) is a class of memory integrated circuits used in computers. DDR SDRAM, also called DDR1 SDRAM, has been superseded by DDR2 SDRAM, DDR3 SDRAM and DDR4 SDRAM. read more

This naming system DDRx-yyyy (where x is the technology generation and yyyy is the DDR clock rate), in theory, is used only for the memory chips. The memory modules – the little printed circuit boards to where the memory chips are soldered – use a different naming system: PCx-zzzz, where x is the technology generation and zzzz is the maximum theoretical transfer rate (a.k.a. maximum bandwidth). read more

DDR SDRAM is a double data rate synchronous dynamic random-access memory class of memory integrated circuits used in computers. DDR SDRAM, also called DDR1 SDRAM, has been superseded by DDR2 SDRAM, DDR3 SDRAM and DDR4 SDRAM. read more

Each type of memory is electrically incompatible with the others, starting with the number of pins on a chip (DDR desktop-style DIMMs have 184, and DDR2 and DDR3 each have 240), and DIMMs using each are keyed (or notched) differently so they can't even fit in the wrong kind of socket. read more