How do platform-wide rules differ from community-specific rules?

Reddit operates on a two-layer rule system: a platform-wide Content Policy enforced by Reddit's paid administrators, and community-specific rules enforced by each subreddit's volunteer moderators. The platform-wide Content Policy is non-negotiable and applies everywhere on Reddit, regardless of which subreddit you are in. It prohibits content categories that Reddit has determined are harmful to individuals or society at large: illegal content, non-consensual intimate imagery, content sexualizing minors, harassment, doxxing (posting someone's private personal information without consent), and content that incites or promotes real-world violence, among other categories. Violations of the Content Policy can result in account suspension or permanent bans issued by Reddit's administrators, and in extreme cases can lead to criminal referrals. Community-specific rules, by contrast, are set entirely by each subreddit's moderators and can vary enormously from community to community. A subreddit about photography might prohibit unedited snapshots and require only technically accomplished work. A political discussion subreddit might ban all partisan language. A science subreddit might require that all posts link to peer-reviewed research and prohibit anecdotal evidence. Some subreddits are extremely strict about staying narrowly on-topic; others allow broad discussion. Moderators can ban users from their subreddit without involving Reddit administrators at all, and a ban from one subreddit has no effect on a user's ability to participate in other subreddits. The layered system creates a rich ecosystem of community cultures under a common legal and ethical ceiling. Users sometimes find the distinction confusing because the consequences look similar — removal of content or loss of posting access — but a subreddit ban is a local action by volunteers, while an account suspension is a platform action by Reddit employees with much broader implications.