suffix
citizen; resident; person (of a group)
Suffix used to refer to people belonging to a particular nation, region, or group. Common in words like 国民 (citizen), 県民 (prefectural resident), 市民 (city resident).
彼はアメリカ国民だ。
He is a U.S. citizen.
この公園は市民の憩いの場です。
This park is a place of relaxation for the city's residents.
suffix
user (of a website, esp. as a collective)
Colloquial suffix used online to refer to users of a particular platform or service, often with a collective nuance. E.g., ツイッター民 (Twitter users), ネット民 (netizens).
ツイッター民の反応は様々だった。
Reactions from Twitter users were varied.
ネット民の間でその話題が盛り上がっている。
The topic is trending among netizens.