Prevents the search engines from indexing your search result pages, by a
robots tag to them. The
part means that search engine crawlers will
spider the pages listed in the search results.
(warning: don’t enable this if you have the minimeta widget
The above two options prevent the search engines from indexing your login, register and admin pages.
Prevent the search engines from indexing your subpages, if you want them to only index your category and / or tag archives.
By default, WordPress creates author archives for each user, usually available under
/author/username. If you have sufficient other archives, or yours is a one person blog, there’s no need and you can best disable them or prevent search engines from indexing them.
If you want to offer your users the option of crawling your site by date, but have ample other ways for the search engines to find the content on your site, I highly encourage you to prevent your date-based archives from being indexed.
If you’re using tags as your only way of structure on your site, you would probably be better off when you prevent your categories from being indexed.
Read the categories explanation above for categories and switch the words category and tag around
Prevents archive.org and Google from putting copies of your pages into their archive/cache.to put copies of your pages into their archive/cache.