Unified Write Filter (UWF) provides an extra layer of protection to write-sensitive media, e.g. Solid-State Drives (SSDs). Instead of writing directly to the SSD, an overlay can be used and written to instead. For example, if I had an SSD that I wanted to extend the life of, I might place an overlay on it and have that overlay stored on a Hard Disk Drive (HDD). I would then change settings for folders on the SSD to be excluded from UWF that I know I want a performance boost from, e.g. Program Files. I could even be more specific and only have certain programs excluded from UWF, e.g. I might exclude my video editing software since I dabble in video editing as a hobby.