Age is a huge factor in SEO, because age indicates trust.

Age implies trust, because the longer a spammer has been around, the more chance people have had to report it as spam. So the longer it has been around and gone unreported, the less likely it is spam. Indeed, spammy sites tend to get reported quickly and banned from appearing in search results, so they tend to move on quickly to new domains with new content. Like a criminal on the run; spammers keep moving on, so they always have new chances to trick new people.

Age value is applied to URLs, content within URLs, and inlinks.

URLs

Check out, examples of how URL age is important for SEO.

Why do older sites rank higher?

Age of URL (and age of domain) is a huge factor in SEO. How long has your URL existed? How long has your domain or webpage been around at its current address (URL)?

Content within URLs

How long have your sentences and pictures existed at their current webpage addresses?

If your page's content has stayed the same for years, search engines trust it to stay the same for a few days longer; so your page will rank higher. Search engines are not so keen to send you somewhere that was relevant to your search term a few days age (when the page was last cached by the search engine) but is likely to be irrelevant to your search term now (due to frequently-changing content).

Index pages & news portals

Old content is great, especially for article pages. But new content is also great, especially for index pages.

Index pages & news portals, for news sites and other sites which are regularly updated with new pages, should constantly be refreshed with new content to link through to the latest pages. This enourages search engines to check your site regularly, to follow your new links and update their records to acknowledge your new pages. This means that search engines will quickly find your new pages, so you can get traffic relating to new stories that other sites have not yet been seen writing about.

Inlinks

Of all the pages, on your site and on other sites, that link to any given page of yours; how long have these links existed?

It's great when a big site links to your site, but it's even better when that other site has been linking to yours for many years, because this suggests that the other site will continue to be linking to your site for many more years to come, and is generally an indication of trust. Quality of inlink is not about quality of page that links to you, it's also about relevance of that page to your page, and also age that the link has existed.