Put simply, Akismet is a spam filter for your blog. It should be one of the first things you set up and it will help protect your site from a lot of spam. Spam that can be a headache and can even hurt your site's SEO. Imagine having an email account without a spam filter these days? Yes, bad idea. The same applies to your blog.
Akismet should already be in your blog. However, there are a few steps to activate it. First, click on the Plugin tab in the left hand side of WordPress and find the Akismet Plugin. Under this plugin, choose to Activate.
This will take you to a page in your Settings where you can click to set up your Akismet account.
Set Up Your Akismet Account
Once you have chosen to set up your account, it will take you to Akismet's pricing page, where you can select Personal > Name Your Price. This is the choice on the left hand side.
You'll notice a preset price to the right. Slide that back to zero. Fill out the rest of the information and check the three boxes if they apply.
From here, you will proceed to checkout, which will include signing in or creating a new account. This should be free.
Copy & Paste Your API Key
Once you have signed in and proceeded through checkout, you'll finally get your API Key. Choose to Copy.
Last, you'll go back to WordPress and in your Settings choose Akismet Anti-Spam, and click to Manually Enter an API Key. From there, paste the in code to complete the activation!
Nicely done! Akismet will now take care of spam on your site.