could somebody clarify what the meaning
pseudo file system means and how is it different to a regular
file system from different point views (users/processes/apps) .
'Pseudo-' means false, pretend. So "pseudo-filesystem" means a filesystem that doesn't have actual files – rather, it has virtual entries that the filesystem itself makes up on the spot.
/proc on many OSes is a procfs which dynamically generates directories for every process. Similarly,
/sys on Linux generates files and directories to represent hardware layouts. There are FUSE-based pseudo-filesystems for a lot of things.
/dev may be a real filesystem (just a subdirectory of
/), or a virtual pseudo-filesystem (e.g. devfs), or a middle point such as Linux devtmpfs (which is a full in-memory filesystem but still creates device nodes out of nowhere).
A pseudo file system maintains information about the currently running system
this information doesn't persist across reboots. It exists while the system in running only in RAM; in Window this would be the
/dev this includes things like
/dev/ttyS# they indicate devices as they are connected and they be created dynamically
/sys shows a representation of the physical devices in the machine
/proc maintain alot of info about the current control set
free command is just importing info from