How does google determine the date a thread was posted?

When you search in google, when searching for a term, you can click "Discussion" on the left hand side of the page. This will lead you to forum based discussions which you can select. I was in the process of designing a discussion board for a usergroup and I would like for google to index my data with post time.

You can filter the results by "Any Time" - "Past Hour" - "Past 24 Hours" 开发者_开发知识库- "Past Week" - etc.

What is the best way to ensure that the post date is communicated to google? RSS feed for thread? Special HTML label tag with particular id? Or some other method?

Google continually improves their heuristics and as such, I don't think there are any (publicly known) rules for what you describe. In fact, I just did a discussion search myself and found the resulting pages to have wildly differing layouts, and not all of them have RSS feeds or use standard forum software. I would just guess that Google looks for common indicators such as Post #, Author, Date.

Time-based filtering is mostly based on how frequently Google indexes your page and identifies new content (although discussion pages could also be filtered based on individual post dates, which is once again totally up to Google). Just guessing, but it might also help to add Last-Modified headers to your pages.

I believe Google will simply look at when the content appeared. No need for parsing there, and no special treatment required on your end.

i once read a paper from a googler (a paper i sadly can't find anymore, if somebody finds it, please give me a note) where it was outlines. a lot of formulas and so on, but the bottom line was: google has analyzed the structure of the top forum systems on the web. it does not use a page metaphor to analyse it, but breaks the forum down into topics, threads and posts.

so basically, if you use a standard, popular forum system, google knows that it is a forum and puts you into the discussion segment. if you build your own forum software it is probably best to use existing, established forum conventions (topics, threads, posts, authors....).