How to create additional Steam library folders
Creating additional Steam library folders means that if you have more than 1 drive on your computer you can create Steam game folders onto those other drives as well.
So an example: say you have 1 SSD for your OS, programs, etc. and an HDD that you use for storage. You can keep games you actively play on the SSD and create an additional library folder onto the HDD and use the HDD for games that do not require a fast drive, very big games you can't fit on your SSD or to keep games you're not currently playing. Once you start playing them or if you get more space on your SSD you can then transfer them over to the other library folder.
Step-by-step walk-through:
1. In the upper-left corner click on Steam and then Settings.
2. Click on the Downloads tab.
3. Click on the Steam Library Folders button.
4. Click on the Add Library Folder button.
5. Click the drop-down menu at the top and select the drive that you want to create a library folder on.
From here either select a folder you've already created, or click on the New Folder... button, name it and click on OK.
This video was created in relation to the following Steam Guide: https://steamcommunity.com/sharedfiles/filedetails/?id=1912418281
This video was created in relation to the following /r/Steam Reddit wiki page: https://www.reddit.com/r/Steam/wiki/transferringgames