What is the difference between joining a community and simply visiting it?

Joining a community on Reddit and visiting one are functionally quite different, even though both allow you to read posts and — in most communities — leave comments. The distinction comes down to three main effects: feed integration, navigation convenience, and certain community filtering behaviors. When you join a community by clicking the Join button, that community's posts begin appearing in your Home feed automatically. The community is also added to your sidebar list under "My Communities," making it easy to navigate back to with a single click. If you visit a community without joining, none of these integration effects occur — you can read and even comment on posts, but the community produces no entries in your feed and does not appear in your sidebar. You would need to navigate back to it manually by searching or typing the URL directly. According to r/modnews announcements about the subscription model, Reddit changed the "Subscribe/Unsubscribe" language to "Join/Leave" to make this distinction clearer, since many new users assumed subscribing required a payment or email commitment. Joining is always free and can be reversed by clicking Leave at any time. There is also a subtle permission-related difference. Some communities use Reddit's Crowd Control feature at its highest setting, which automatically collapses or removes comments from accounts that have not joined the community. This means that in certain communities, simply visiting and commenting without joining could result in your comments being collapsed from view by default. Joining the community removes you from this category. As noted in r/NewToReddit discussions, this Crowd Control behavior is the only case where joinedness directly affects your ability to be seen in a community. For all other subreddits without aggressive Crowd Control settings, visiting without joining gives you effectively the same reading and participation rights as a member.