If your website has an XML sitemap, Change Frequencies and Priority are two important tags for supplying data to the search engines. They affect when and how often search engine “spiders” (also called “robots” or “crawlers”) visit your site’s individual pages, which has various implications. Although using the Change frequency and Priority XML sitemap tags is voluntary, they remain important for several reasons…
According to Google.com, the Change frequency XML tag may be set to one of seven frequencies: “never”, “yearly”, “monthly”, “weekly”, “daily”, “hourly”, or “always”. This tells the search engines approximately how often each page is updated. An update refers to actual changes to the HTML code or text of the page, not updated Flash content or modified images. Change frequency examples…
NEVER: Old news stories, press releases, etc.
YEARLY: Contact, “About Us”, login, registration pages.
MONTHLY: FAQs, instructions, occasionally updated articles.
WEEKLY: Product info pages, website directories.
DAILY: Blog entry index, classifieds, small message board.
HOURLY: Major news site, weather information, forum.
ALWAYS: Stock market data, social bookmarking categories.
The Priority XML sitemap tag is useful, although not quite as important. It is set to a number ranging from zero to one; if no number is assigned, a page’s priority is 0.5. A high priority page may be indexed more often and/or appear above other pages from the same site in search results. Here are some examples of different types of pages and how their Priority sitemap XML tag value might be set, depending upon how important they are…
0.8-1.0: Homepage, subdomains, product info, major features.
0.4-0.7: Articles and blog entries, category pages, FAQs.
0.0-0.3: Outdated news, info that has become irrelevant.
How strictly they want to follow the Priority and Change frequency sitemap specifications is up to the search engines; these XML tags are considered preferences, not orders. This doesn’t mean search engines don’t consider Priority and Change frequency important, just that they won’t put sitemap instructions before their own interests (like making sure a site hasn’t changed its subject or become pornographic).
But why is it important when or how frequently search engine “spiders” index your pages? When a “spider” visits a web page, it records information about the page’s content, title, META tags, links, and other characteristics. This ensures that search results reflect its latest content and take into account any recent improvements (such as new META tags or repaired links).
However, it is unnecessary for “spiders” to regularly scan pages that are seldom or never updated. Spider indexing consumes bandwidth (which can increase the cost of operating your website), and may briefly slow access to your site if it is run on a low-capacity server. Thus it is important to set the Change frequency sitemap tag to accurately reflect how often individual pages are updated.
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