Hello I Manage a site for online ads, and I want to ask you how is best to proceed with ads that have expired. To delete them from the server and give 404 not found, or to redirect 301 to the category in which the advert was. Thank You
Either approach may be right, depending on the situation. Here's what I do. First look at the entry traffic for the page (search results, direct, and backlink clicks). If there is none or very little, I'm most likely to let the page be 404 or 410. I'm not a fan of piling up a lot of 301 redirects.
If there is some site entry traffic to that url, then I still have a judgement call to make. A 301 to a relatively generic page is not going to bring much benefit to the visitor. So I reserve the 301 for those situations where there is a nicely targeted "replacement" page. After all, the 301 means that the same information is available at a new url, not "I want to hold this entry traffic in a death grip."
If the entry traffic is very strong, I would probably re-write the content and serve it at the exact same url.