WIkipedia has this definition:
Spam is the use of electronic messaging systems (including most broadcast media, digital delivery systems) to send unsolicited bulk messages indiscriminately. While the most widely recognized form of spam is e-mail spam, the term is applied to similar abuses in other media: instant messaging spam,Usenet newsgroup spam, Web search engine spam, spam in blogs, wiki spam, online classified adsspam, mobile phone messaging spam, Internet forum spam, junk fax transmissions, social networkingspam, television advertising and file sharing network spam.
One of the types, spam in blogs, is a problem for any of my clients which build an Artificially Intelligent Website (TM).
In order to combat this type of Spam, WordPress has offered a service called Akismet for a long time, and is integrated into the main menu under the Dashboard in WordPress 3.0. Over the years, Akismet has protected blogs from over 17.5 billion (with a “B”) potential spam comments.
In order to use Akismet, you only need to procure an API Key from www.Akismet.com. The key is free for personal use, and they only ask large companies or bloggers who make “mad money” (which they define as making more than $500 a month from their blog) to donate $5 a month.
While I could list all of the information about the service, I want to point you to the Akismet FAQ page which does a great job listing the most obvious questions and showing you where to sign up.
It will only take about 5 minutes to get the website connected with the service, however; it can save you substantial time and annoyance having to deal with obviously spammy comments.
Finally, protect your company from lost sales by making sure undesired and unwanted comments are not on your website potentially offending new clients and / or customers.
Empower your website to work for you, while you work on something else.