You guys are starting to get above my pay grade.
Basically, computer storage is constantly evolving, getting smaller/faster/cheaper, but a lot of the past standards like SATA (which is what your PC uses) are still common and drives with that interface are readily available.
The SATA interface was used in both desktops and laptops. SATA desktop mechanical spinning disk hard drives are 3.5" wide and laptop drives are much smaller and thinner at 2.5" wide. But while their power requirements differ (desktop drives require more juice), the power and data connections are identical. The is no reason you can't use 2.5" laptop drives in a desktop computer if you want to without any issues whatsoever beyond figuring out a way to mount them in the case. Cheap 2.5" to 3.5" drive adapters of varying styles make that easy. Lots of PC cases started coming with places for 2.5" drives to mount to.
Solid State Drives became mainstream when SATA was king. SSDs remove almost all of the latency from data reads/writes so they make any computer 'feel' a whole lot faster even though the SATA bus itself isn't any faster. SSDs just make lots better use of it.
SATA SSDs are made in only the 2.5" size since there is no reason at all to make one that's physically as large as a 3.5" desktop drive. They can be used in laptops and desktops and are a very easy and now-cheap way to bring new life into an old computer. The computer doesn't know or care that the hard drive attached to it is solid state since all the drive electronics are standards-based and backwards-compatible.
The only real issue with SSD hard drives (from a general-use PC or laptop standpoint) is that they are more expensive for the amount of storage you get when compared with a mechanical spinning drive. But the prices have come down so much over the years that it's not really an issue, especially when taking the amount of performance gained into account.
So if your drive is on the way out and you want to keep your computer running since it's doing everything you need it to do, spending like $50 and some time to swap it out and reinstall a newer version of Windows is a cheap and easy way to get a few more years out of it.
An old 4th gen i7 with 12GB of RAM and an SSD would be plenty fast for most tasks. My wife's decade-old homebuilt PC has a 3rd gen i5, 16GB and an SSD running Windows 10 and she still uses it with Adobe Creative Cloud and games on it.
