An SSD is a Solid State Drive. This is a hard drive with no moving parts, meaning that there is no hard drive platter to spin, there are no motors and it and you do not wait for it to start. The speed of reading and writing to an SSD is much faster than a traditional hard drive.
I have just installed an SSD into my Mac Pro and I’m amazed at how much faster that is to use Vectorworks. Selecting tools, selecting objects, updating the Object Info palette… everything just seems much faster. It was reasonably easy to install and I took the opportunity to also install a latest version of the Macintosh operating system. A new operating systems is not without its challenges, but that’s for another post.