Content freshness is definitely a factor in search engine algorithms. For news items and blog posts, in particular, freshness gives a boost in rankings. Several major search engines have filed patents for gathering historical data about pages so not only is this a current factor but it is likely to be one that search engines will be adapting and improving over time to ensure that their customers receive timely and relevant results.
The big question, of course, is what does this mean to the site owner in terms of updating their content. Is it necessary to update pages frequently to get good results? The answer to this question is: it depends.
One of the main reasons that a site should try to feature fresh content is because it can increase the frequency of visits by search engine spiders. Naturally, if you are updating pages on a regular basis, you want that to be reflected in search engine indexes and you want the search engines to return in a timely fashion so that new information can appear in search engine indexes. Studies in index freshness have shown that, for over 68% of pages, Google requires about two days before the page is visible in the index. Yahoo is quicker — over 50% appear within a day.
However, search engines don’t crawl your site every day unless they have a reason and if they are only coming around every two weeks, this means that a page that you updated today might not appear in the indexes for over two weeks and that’s assuming that they actually accessed the page since they do not access every page every time they come. If your site is publishing timely news items or pages that need to be accessed quickly, content freshness is important. The good news is that these items are inherently fresh. Search engines will notice this and will return often to find your new content.
So, what if you are not publishing news items every day but you still want search engines to visit often? Should you try to change the content of your homepage every couple of days? Optimizing the content of a page so that it will rank well for a key phrase can be an arduous and painstaking process involving a lot of tweaking and experimenting before the page is just right. Changing the content of the page every day just for the sake of change is not a good idea. What about just updating the page by adding a word here and there? This is also not a good idea for two reasons:
Content freshness is actually one of the best reasons to include a blog on your site. You can take the opportunity to provide your visitors with timely news about your company and industry and even feature the occasional quick link to any new pages that you may have added. A well-written blog post has the advantage of actually being new content. Just make sure you post regularly. A regular pattern of adding new pages of content is the best encouragement for search engines to return on a regular basis.
Furthermore, if you do manage to convince search engines to visit your site regularly, it’s a good idea to make it easier to find those new pages. In other words, don’t update pages just to make old content look new. Only update pages that really do contain new content and then allow search engines to see that the content is new by setting your server to support Conditional Get or the If-Modified-Since request-header field. That way search engines are much more likely to find your new pages when they come and put them into search engine indexes to be found by your potential new visitors as soon as possible.