I was also first confused about this particular file running in my processes list, here is a quick look at what is the importance of the file smss.exe
It should be noted that the SMSS.exe file is always located in the C:\Windows\System32 folder.
Any other location is considered to be a trojan or virus or a spyware.
There are many processes that run behind the scenes in Window's operating systems. One of these processes that may look suspicious is the Glossary Link SMSS.exe. This is an execution file with the full name Session Management Subsystem.
The Session Manager Subsystem is responsible for starting a user's session. When this process begins, the system Glossary Link thread is responsible for a number of specific tasks including launching the Winlogon, specific Win32 processes and among other items, setting the system variables.