The advantage of using a solid-state drive (SSD) over a hard disk drive (HDD) primarily lies in its speed and performance. SSDs utilize flash memory to store data, resulting in significantly faster read and write speeds compared to HDDs, which rely on mechanical spinning disks. This speed translates to quicker boot times, faster application loading, and improved overall system responsiveness. Additionally, SSDs are more durable and consume less power, making them a preferable choice for modern computing needs.