Akismet is one of many spam-fighting plug-ins developers created for WordPress.
However, it has a special distinction: Automattic, the same folks who built WordPress,
makes it. It’s also the only spam-blocking tool with which WordPress.com blogs work.
Akismet works by intercepting each new comment. It sends the details of that comment
(including its text and the commenter’s website, email, and IP addresses) to
one of Akismet’s web servers. There, the server analyzes it, using some crafty code
and a secret spam-fighting database, to attempt to determine whether it’s legitimate.
Any one of a number of details can betray a spam message, including links to
known spam sites, a known spammer IP address, phrases commonly found in spam
messages (“free Viagra” for instance), and so on. Akismet quickly makes its decision
and reports back to your website. Your site then either publishes the comment or
puts it in the Spam folder, depending on Akismet’s judgment.
WordPress experts report that Akismet’s success rate hovers at around 97 percent.
Usually, when Akismet errs, it does so by flagging a safe comment as spam (rather
than allowing real spam through). However, Akismet’s success depends on the site
and the timing. When spammers adjust their tactics, it may take Akismet a little
time to catch up, during which its accuracy will drop.
NOTE Akismet uses an honor system, and there are plenty of sites that earn a bit of money but don’t pay
the Akismet fee. If you want a totally free business-friendly solution for a self-hosted site, you need to find a
different plug-in. Several good alternatives are described in the box below.