Before getting into the best WordPress plugins out there, let’s cover a couple of definitions for the uninitiated among us.

WordPress is the world’s most widely-used open source Content Management System (CMS). While it is often used as a blog, WordPress is powerful enough to run entire websites. So it isn’t just a blogging platform. WordPress is powered by PHP and MySQL, and has exciting features such as templates and plugins that make building great websites relatively easy. WordPress is used by 13% of the 1,000,000 biggest websites in the world, no small feat considering the breadth of options available.

Plugins are simply applications that enhance the capabilities of WordPress and make it easier to work with. Most plugins are free.

Today, we’d like to share with you the 5-best and most essential WordPress plugins out there. Our opinions are highly subjective, but these are plugins we want you to know about.

#1: All-in-One SEO Pack

The All-in-One SEO Pack makes on-page search engine optimization easy. For this reason, it’s our top pick. With this plugin, adding Meta tags such as title tags, meta descriptions, and keywords has never been easier. This is a good thing, as too many websites are missing these important elements (and missing out on online lead generation and/or online sales as a result).

#2: Askimet

Askimet allows you to stop moderating comments. It automatically checks comments left on your website against the Askimet web service to see if they look like spam or not. If it’s spam, they toss the comment out. To keep the service honest, you can review the spam it catches to make sure the plugin is doing its job correctly. Here’s the thing: it does. We’ve been using it for months, and it just works. Period. There are two things that make using this plugin essential. One, your readers will never have to type in a CAPTCHA again. Two, your readers will never have to wait for their comment to be moderated again (this drives us nuts when we visit other blogs!).

#3: Google XML Sitemaps

Google XML Sitemaps will generate a special XML sitemap which will help search engines to better index your blog. If that sentence makes your head hurt, just know this: it makes it easier for Google to read your website. That’s a good thing. If Google can’t or doesn’t read your website, that’s bad. You want them to read it so they can share your website with people that use the Internet and have money burning a hole in their pocket. Consider this an essential WordPress plugin if you prefer to trade your labor and/or skills for money.

#4 Subscribe to Comments Reloaded

Consider this one a cherry on the top of your delicious WordPress sundae. Subscribe to Comments Reloaded will change the way people use your blog. Without it, people just stop in, leave a comment, and never return. With this plugin, your readers can click a box saying they wish to be notified of follow-up comments via email. This email notification will (in some cases) cause the reader to return and leave a comment. This will give you more Web traffic, more comments, and it will make your blog more conversational. That’s what we all want right? I hope so! Curious how it works? Leave a comment to this post and then click the box to subscribe to follow up comments!

#5: TweetMeme

Guy Kawasaki once called this the most important button on the Internet. It probably isn’t at that level today, but it is certainly still highly effective when it comes to getting your message to the masses. Twitter has proven to be a highly effective viral marketing tool. If you have something important or interesting to say, odds are Twitter will go a long way in getting your voice heard. Within the Twitter-sphere, there is nothing more valuable than a ReTweet. A ReTweet occurs when someone that reads your content re-broadcasts it to all of their followers. When this happens, viral marketing magic happens. TweetMeme makes it easy for your blogs’ readers to ReTweet your content, which will bring you more traffic, more comments, and (hopefully) more business.

That’s our list. Do you agree? Do you disagree? Did we leave something off of our list? Would you like to suggest a plugin that should have made the cut? Let us know in the comments! And as always, thanks for reading.