What are meta tags?
For those who don’t know, a meta tag is an HTML tag that resides in the <head> section of a web page. Unlike other HTML tags, meta tags do not appear anywhere on the page itself, so most visitors never see them. Different meta tags serve different purposes, but they are generally used to provide additional information about the page. The meta description tag, for example, provides a brief summary of the page’s content. How this information gets used varies from tag to tag.
Examples of meta tags:
<meta name="distribution" content="global" />
<meta name="language" content="en, sv" />
Which meta tags are worthwhile?
There are a lot of meta tags out there, but very few of them are useful. In fact, chances are good that a site that doesn’t use any meta tags at all will function just as well as a site that does. Some have their uses, however, particularly when communicating with search engine spiders. Here’s the breakdown of every meta tag you’re likely to come across:
Abstract – Use the meta description tag instead.
Author – Sure, it’s nice to plaster your name all over your content. However, the best place to do that is somewhere in the content itself to avoid confusion.
Cache-Control – It’s historical use has been to keep users from seeing outdated versions of your website. Since this is rarely an issue nowadays, it’s no longer as useful. Note, also, that it will do next to nothing to prevent your site from being cached by search engines; you should use the robots meta tag for that purpose.
Classification – Considering how badly spammed the keywords meta tag has been, I can’t see such an arbitrary tag doing any better.
Content-Language – This one’s iffy. Ascertaining the language of the content on a site is rarely a big issue. Use it only if you need to clarify from one page to the next, such as if you have multiple translations of the same page.
Content-Type – This one’s actually important. You can assign the character set of a page using one of several methods, including the content-type meta tag. Make sure you do so in some way on every page.
Copyright – Like the author meta tag, you probably should add the copyright notice directly to the body of your website.
Description – Although its no longer useful for ranking purposes, the description tag is often still used in generating snippets (the text that appears beneath the title in the search engine result pages). It is, therefore, a very powerful tool for drawing in potential visitors. Never underestimate the power of controlling each page’s marketing message to the world.
Designer – The same as author and copyright tags, insert this on the website itself.
Distribution – If a page is meant for internal distribution only, it should be properly blocked using robots.txt or the robots meta tag (below). This tag is completely unnecessary.
Expires – If you have content that shouldn’t be crawled or indexed after a certain period of time, it might be useful. For bloggers, the occasion will probably never arise.
Generator – This one is only used by automated web authoring software, so there’s no point to input it by hand.
GoogleBot – If you have some dire need to instruct one search engine spider differently than another, go ahead.
Keywords – Once upon a time, this might have been useful. Since it was so frequently spammed, however, it no longer carries any ranking benefit. It’s still commonly used, however, and it might even be worthwhile in second-rate search engines, but it won’t get you anywhere with the big boys. If you choose to use it, do not, but do not stuff it!
MSNBot – See the note about the googlebot meta tag.
Owner – See the note about the author meta tag.
PICS-Label – See the note about the rating meta tag.
Pragma – Telling browsers whether or not to cache your page could be handy for usability depending on your site. However, I’ve heard that it doesn’t enjoy a lot of support.
Publisher – See the note about the generator meta tag.
Rating – Like so many web standards, it would be great if it were actually used. However, the sites that deserve a rating of “Mature” or “Restricted” rarely broadcast it. Don’t bother with it; let the rating of your content speak for itself.
Refresh – If you’re redirecting one page to another, use a 301 redirect. Meta refreshes are generally regarded as spam.
Reply-To – See the note about the author meta tag.
Revisit-After – Even if getting frequent visits from search engine spiders offered any competitive advantage (it doesn’t), they aren’t going to visit your site more frequently just because you ask them to. This one’s only useful for limiting the frequency of spidering, not increasing it.
Robots – Although you can use the robots.txt file to issue site-wide directives to search engines, the robots meta tag is very handy for controlling spidering on a page-by-page basis. You can tell search engines whether a page should be indexed, whether it should be archived, whether or not its links should be followed, and even how to generate its search result snippet.
Subject – Your title tag should communicate your subject; using a meta tag to do so is unnecessary.
Title – Don’t bother with the meta title tag when your ordinary title tag does the job much better.
Unavailable-After – Believe it or not, this one’s brand new and supported by Google. Why they didn’t just go with the expires meta tag is anyone’s guess. At any rate, like it’s identical twin, it will rarely if ever be useful for bloggers.
There are literally dozens more meta tags out there, few of which enjoy any widespread use. When in doubt about whether a meta tag is worthwhile or not, it’s probably best to assume it isn’t. Otherwise, you’ll just end up cluttering your page headers with a lot of useless junk.