Block posts from a certain category from all but the home page, for example

Sorry if there’s been a post about this, or there’s an obvious workaround, but…

I’d like to have posts in a certain category, in my case, “Site Announcements”, be displayed only among the posts on the home page (home.php template) but not in any other case (search by category, author, etc.). What plugins or code would I need to use for this? Any ideas? Thanks everyone, you’ve been great so far…