I'm not well versed in server admin stuff, but I notice the user groups psaserv and
psacli psacln come up all the time on different systems. I assume these group names are commonly used for a particular purpose/role. Is that true? Like what?
These groups are created by Plesk, a common server administration panel that is generally used on web servers hosting websites.
psaserv group is used for the server-side management scripts and also for parent-level directories that should not be shared between different websites.
I have not seen a
psacli group, but on normal Plesk installations there is the alternative
psacln. This group is used for client-side files, such as all of the files held within a website.