Storage is required for the operating system, games and files. There two types of storage that are noteworthy, Solid State Drives (SSD), Hard Disk Drive (HDD) without going into much details, SSD's support higher data throughput than HDD's, don't have moving parts; noiseless operation, come as 2.5" (laptop HDD size) but it's price-per-GB is significantly higher than HDD's

HDD's come in 2 distinct size 2.5" (laptop size), 3.5". Most gaming cases have support for both so having and SSD & HDD in your gaming system isn't an issue.

That said, I'd recommend an SSD to store the OS and programs to reduces loading times. HDD's been cheaper can be used to store games, music, videos and photos. However, if you got the funds available you can have all SSD's in your gaming machine.

For an indepth explanation see this post -https://www.nairaland.com/2620267/difference-between-ssd-hard-drives

Related post - https://www.nairaland.com/3267973/gaming-pc-what-need-know

Most of the SSDs i've seen and the most popular ones are made by Samsung. Eg. Samsung 750 Evo. Aren't there other models??

Lana1:
Most of the SSDs i've seen and the most popular ones are made by Samsung. Eg. Samsung 750 Evo. Aren't there other models??

There are several SSD manufacturers and what ever one you choose for a gaming PC will give you a significant boost compared to HDDs. So I tend not to recommended any particular brand. A quick Google search will reveal many.

What's noteworthy is if you choose an SSD for only the OS, the recommended size is a 120GB as the bare-minimum. A fresh install of Windows 10 for instance, will comfortably fit in a 60GB SSD with some favourite programs but when you factor in the price difference it's cheaper to get the 120GB capacity.