Here is some more information about Akismet, in case you never heard of it.
Akismet provides an online service that will tell you whether a comment submitted to your website is spam or not. In addition it will also allow you to flag messages as comment. This is basically the same as flagging emails as spam in your Gmail or Hotmail account, for example. Akismet will save the message as spam on their server and add it to their library to determin whether other messages are spam or not.
So the Akismet anti-spam library is updated daily by all the websites connected to it and so everyone connected to Akismet helps prevent spam together. Akismet is most often used in Wordpress blogs because of all the comments posted to the blog posts and it's actually in the top 5 of most popular add-ons for Wordpress.
In order to use the Akismetty package you will need an Akismet api key which you can get by signing up on Wordpress. You can find more information about configuring the package on the configuration page of this documentation and information about how to get an api key on the 'Getting an Api Key' page.