The SSD, or solid-state drive, is a type of internal storage device similar to an HDD (hard-disk drive). The SSD is also often referenced as a solid-state disk, although this term is technically incorrect; SSD does not use the disk mechanism that HDDs do. HDDs and SSDs are both internal storage devices, but this is where the comparison ends--both storage devices contain very different internal hardware and as a result work very differently.
The SSD is essentially a modern version of the HDD. While the HDD contains many internal pieces, such as magnetic platters that store data, the SSD uses flash memory instead and does not contain any moving parts. The SSD uses semiconductor chips, primarily NAND flash memory. Any device that uses semiconductor properties is termed "solid-state". Flash memory is a type of non-volatile ROM memory, meaning that the data will be stored even after the computer is powered off. This is different from volatile memory, such as RAM, which only stores data currently being used.
The SSD is connected to the power supply on the motherboard through SATA cables. On the outside, an SSD looks exactly like an HDD--a thin, metal, rectangular drive. They typically come in two sizes, 2.5 inches and 3.5 inches. This is simply to match the size of HDDs and the drive slots in computers. However, SSDs look very different than HDDs on the inside. Instead of containing many moving parts like the HDD, the interior of an SSD is simply a board with a grid-like pattern where the chips and transistors are located. For more information on the SSD's interior and its flash memory, click here.
Since the SSD does any contain any moving parts, there are several clear advantages to it. For example, it takes less time to access data, does not require as much power, and is simply more reliable and long-lasting than the HDD. Furthermore, it does not generate a sound as it lacks movable parts. These examples are just some of the many upsides to the SSD. In fact, the only real drawback is currently cost. As of 8 years ago, the SSD cost about ten times more per gigabyte than the HDD--a considerable difference in price. Because of this, a standard SSD is often sold with less storage than a standard HDD, in an effort to make it more affordable. For more information comparing the HDD and the SSD, click here.
SSDs originally began to develop in the 1950s and were used a bit during the 1970's and 1980s in IBM computers. However, they were extremely pricey and not really known about or used until the 1990's. For a more detailed history of the SSD, click here. As technology continues to advance, SSDs could become more common than HDDs. Since SSDs do not contain internal moving parts, they can be much smaller than HDDs but still hold the same amount of memory, or even more. This gives SSDs versatility moving forward--as the HDD becomes less common, the SSD might not only replace the HDD but could have increasingly more uses as well.