Comments on your WordPress blog are a double-edged sword. They can be great for engagement, but they also leave you open to spam attacks. Wide open, in fact.
Akismet is a popular spam filtering service for WordPress, and it blocks about 7.5 million spam comments every hour. Spam comments can be incredibly frustrating to deal with, so much so, that some bloggers even choose to completely disable the commenting facility on their websites.
Instead of going to that extreme however, there is a simple solution that also doesn't involve replacing the native WordPress comment system with an external one like Facebook or Disqus.
Add CAPTCHA to your comment form to practically eliminate spam
Step 1. The easiest and fastest way to get started with this is to install the plugin reCAPTCHA in WP comments form. After you activating it, you'll need to get a pair of "keys" from Google (see Step 2).
Step 2. Register your website at Google reCAPTCHA. Click "Admin Console" in the top menu bar and login to your Google account when prompted. After you're logged in, hit the plus button to register your site for reCAPTCHA.
Enter your domain name in the label field and in the domains field where it says "Add a Domain". The reCAPTCHA type is largely a matter of preference, and some plugins may require one or the other, however, I tend to choose the v2 "I am not a robot" challenge, as in the screenshot below.
Check the Accept the reCAPTCHA Terms of Service checkbox and hit the Submit button. On the next screen, you'll get a Site Key and a Secret Key, which you'll need to copy and paste into the respective fields back in your WordPress dashboard.
Back in your website's WordPress dashboard, head to reCAPTCHA settings and paste the Site Key and Secret Key into the respective fields, hit SAVE and you're basically done. There are a few different customization options to help the CAPTCHA better match the theme of your site, but other than that, you'll get the familiar security check whenever you (or anyone else) visits the site without being logged in.
Good riddance to comment spam.